Model 509 - 1949
Suds-o-gun feature added to sprayer. Hose redesigned -- still gray with red/silver stripes, but new chrome-plated swivel connector added to wand end. Shipping/storage cartons redesigned. Still maroon in color, but new "Kirby Kabinet" introduced for the attachments.
Bag redesigned. Still gray with red/silver lettering, but now, the pair of stripes going up and down the bag are straight down the middle instead of to the left and right as earlier.
Handle grip still gray but now made of smooth plastic instead of ribbed rubber.
Light housing trim now one single piece of gray rubber that goes around the front-most edge and then along the sides, to about half-way back.
Major changes in factory production were made with the 509-512 series, mostly involving the way that the motor, rug nozzle, and fan-case housing were made. I do not know very much about the different casting processes, so maybe someone can fill in these holes for me. If you look at the inside surfaces of these three housing components, the inner surfaces of pre-509 versions are rough and sort of crude-looking -- with a sort of "grainy" surface. With the 510 and later models, the inside surfaces are as smooth as the outer surfaces are, but not polished out of course. I believe the earlier version was "sand casting" and later it was "dye casting" but I may be wrong about this.
Model 510 - 1950
First mention in literature of "triple cushion vibration" feature of rug nozzle. Handi-butler first introduced.
"Sweet-Aire" dispenser added to Sani-emptor. Earliest ones had gray plastic thumb-screw on Sani-Emptor to apply the liquid Sweet-Aire. Gray screw-tips are very scarce, I have only seen one or two. All others were red as they were until the 562. "Sweet-Aire" liquid came in a small glass bottle with two caps -- one sealed, and one with a hollow, pointed metal tip sort of like a blunt hypodermic needle.
Belt lifter logo (and in fact the Kirby logo in general) slightly changed and updated. A little more sleek and streamlined, but still in a cursive script. (A bit of trivia... the original cursive Kirby logo was based upon the signature of inventor Jim Kirby!)
Wands in new ribbed finish instead of smooth as earlier. Portable handle grip now painted in gray hammertone.
Model 511 - 1951
According to some Kirby sales literature, this model did not exist. Supposedly, no machines were manufactured in 1951 due to the outbreak of the Korean war. But I have not only a 511 machine, but a 511 instruction booklet as well!
Although, as far as I can tell from machines I have seen over the years, the 510 and 511 are literally identical other than the model number, so perhaps the same machine was made with a new model number in order to keep the model numbers consistent with the years of production even though a different machine PER SE was not manufactured. (Wouldn't be the first time this has happened)
(Also note that in fact, the same identical instruction booklet, other than different-color covers and revised model numbers, was supplied for models 510 - 515!!)
Model 512 - 1952
I do not know of any changes from 511-512 other than model number designation.
Model 513 - 1953
Updated, more attractive color scheme. Wheels still black vulcanized rubber; handle grip still gray* and front rug nozzle bumper now red plastic, and light housing bumper now bright red rubber. New stainless-steel rug guard added to bottom of rug nozzle that runs the entire length of the nozzle.
Attachments still gray ribbed plastic, hose still gray cloth with red and silver stripes. "Massage cup" now made of plastic instead of rubber and improved with new comb-like protrusions.
A smaller, but higher-torque motor was provided. (Sorry, I don't know the technical details or amp ratings)
New style bag with new logo. The leg of the "K" and the leg of the "Y" come down the front of the bag and meet at the bottom in a point, making a long, narrow, v-shape down the front of the bag. Bag fabric plain gray corduory material. Bag still has chrome-ball type chain, but the end that attaches to handle has the same longer looped wire "attacher" as the cord has had ever since the 505, instead of just the circular wire ring.
513 still had all-red belt lifter with older-style logo -- so the logo on the bag was the newer one, but the logo on the belt lifter was the earlier one, so they did not match. Kinda odd!
New "push-push" on/off switch with larger chromeplated toe-button mounted on top of switch housing instead of on side. Motor turns on with first push, turns off with second push. (Earlier Kirby switch, as far back as I have seen [except for rare handle-switch model], was a small, side-mounted toggle switch.)
I originally had believed, and had said here, that the 513 was the first model to have a red handle grip. However, a Kirby expert emailed me with the information that all the 510-513 handle grips were originally gray plastic; he said the first red ones did not come out iuntil the 514 when the handle shape was changed and the swivel cord hook was added. He said that any machines 513 and earlier with red handle grips had replacement grips.
I am not sure I completely buy that, as I have seen so many 513s with red handle grips, and the grips did appear to be original. (There is a difference between original, pre-514 Kirby grips and after-market replacements -- see photos). However, this guy is older and wise than me so for time time being I will let his correction stand, unless and until I get clear information to the contrary.
Of course, it may be that we are both right -- that the first 513s had gray grips and then as changes for the 514 were being made, the color of the grip was updated to red. Not that it really matters in the grand scheme of things, of course, but the whole point in compiling this report is to finally clear up the many ambigiuties about these machines for people who want to faithfully restore them for their collection.
Model 514 - 1954
New re-designed, larger, more comfortable plastic handle grip in new red color to match other trim, and new flip-down top cord hook for quick cord release. New gray cord made with plastic outer insulation instead of rubber, with new Kirby logo on plug and and new cord clip integrated into the molded plug end to allow it to be clipped to the cord for storage. Also, here's an obscure detail that probably most people have overlooked: The screw for tightening the handle-grip onto the long middle part of the handle was reversed in position from the left to the right side, apparently to favor right-handed repair technicians!
Same gray bag as 513 with V-shaped stripe, but 514 bag has a pronounced mottled pattern running through the fabric (but not the silvery-speckled fabric of the 519 and later), instead of a smooth gray finish.
Modernized red plastic belt lifter with new, more angular, straight-lined, modernized style "Kirby" cursive logo in red lettering against a silver background.
Improved floor polisher nozzle with more, and denser, tufts of polishing bristles. Bristles now in straight rows instead of in curved rows as earlier.
Handle fork now "filled in" at bottom instead of hollow.
Model 515 - 1955
New bag lettering greatly simplified. Now just a Kirby logo in a circle, no V shapes or stripes. Bag still plain gray in color (no texture or pattern).
New 10-bladed fan.
New wheels of smooth, gray Dupont "alathon" plastic instead of black vulcanized rubber. (Same wheels as on completely redesigned 516.)