This is similar to what goes in the holes in the door on BENNETT a 646, 766, 966, etc.
Door bumpers to Keep the operating noise down.

https://www.grainger.com/product/16WC62?gclid=Cj0KCQjwuJz3BRDTARIsAMg-HxVgov-eriYSRssgWsSY9kremt0Zb4jIe9xGpzlBPn1C417-_o522roaAq_3EALw_wcB&cm_mmc=PPC:+Google+PLA&ef_id=Cj0KCQjwuJz3BRDTARIsAMg-HxVgov-eriYSRssgWsSY9kremt0Zb4jIe9xGpzlBPn1C417-_o522roaAq_3EALw_wcB:G:s&s_kwcid=AL!2966!3!264955915892!!!g!439969404635!

I literally just ordered something similar from McMaster Carr for my 966.

Tight-Grip Push-In Bumpers for 3/16" ID and 1/16" Thickness, 1/4" Ridge Diameter, 3/16" High, SBR

I still have a few NOS bumpers and they look just like the ones
in the link.
We found a guy that had tons of NOS stuff from the 40's, over 30 yrs ago.
A case of DINO ad glass for Bennett 766, porcelain spinners , green & red for National A-38
Wayne 60-70 spinners NOS, Tokheim spinners with the colored discs NOS, 76 & 36-B bezels....
All kinds of great stuff , all sold now