In my opinion, any of the self propelled models from G3 thru Sentria are fine regardless of the production date.
The G3's did have problems with the on/off switch, handle pivot spring and the transmission.
All G3 replacement parts are now same as Sentria with the exception of the color. The belt lifter, rug plate, emptor & fill tube have also been redesigned as well to Sentria specifications.
I am currently in the process of rebuilding my G3 and my sister's G4.
On my "early" G3, I am replacing the fan, transmission & rear wheels & caps, handle pivot spring, power switch, brush roll, cord, belt lifter, front wheels & caps, bag, emptor & fill tube.
On my sisters G4, I am replacing the fan, brush roll, cord, belt lifter, wheels & caps, emptor & fill tube.
I may replace the G4 transmission if still noisy when the machine is reassembled. I tore completely it down and cleaned & oiled the clutches, etc. so I will see how it performs under power.
On both G3 & G4 the inner fan case & nozzle are being sandblasted & buffed out. The other chrome parts are being buffed out. The labels are not being disturbed or removed.
Because I am extremely fussy, I would never purchase a "refurbished" model from a dealer. Everyone has a different opinion of what "rebuilt" means. I rather rebuild it myself completely using genuine updated Kirby parts and have the metal sandblasted & buffed.
When buying from a dealer, you don't know what has been replaced, who knows if genuine parts are used and whether the machine is spotless on the inside. A lot of dealers don't care or bother to clean the inside and whether the labels are removed. I've seen some junk people consider "rebuilds" with the inner nozzles painted silver over dirt, yuk!!
Rebuilding these machines have been really fun for me as I know they will be truly refurbished once I am done with them.
My sister also has a G3 and a G6, I'm sure she will want rebuilt after she sees her completed G4.
When Kirby manufactures replacement parts for their older self propelled models, they simply don't make the same part. The parts are brought up to the specifications of the current models. No other manufacturer that I know improves parts for their older models the way Kirby does.
I always was capable of repairing the Kirby, it was the polishing & sandblasting, I did not want to get into due to the mess. This problem has been resolved now that I found a metal polishing & sandblasting shop here in Las Vegas which was very familiar with Kirbys.
I know now that I can do a rebuild that I can be truly satisifed with and on par with the Kirby Rebuilding Dept.
If you have any questions regarding Kirby, don't hesitate to drop me a line.
Ray