Most American made synthesizers from the seventies and early eighties like Moog, ARP, Sequential and Oberheim used Pratt-Read keyboard assemblies. Those keyboards used rubber bushings as dampeners and guides for the keys but these bushings become brittle and/or melt after so many years of usage or storage.

The keyboard become uneven, the keys are sticky and noisy and unpleasant or impossible to play.

To overcome this, you should replace all the bushings and lubricate them with a silicone/PTFE grease.

So, here you can buy a set of bushings with the selected number of keys of your keyboard and a top quality silicone/PTFE grease tube.

Bellow, you can see a list with some synthesizers and the number of keys that use Pratt-Reed keys:

32 keys - Moog Micromoog, early Prodigy models

37 keys - Moog Sattelite, Minitmoog, Oberheim OB-1, 2 voices, Sequential Pro One, ARP Odyssey, Axxe, Pro/DGX, 

               Octave Cat, Kitten, EML 100/101, Paia Proteus

44 keys - Moog Minimoog, Multimoog

49 keys - ARP 2600, Omni, Oberheim 4 voices, 8 voices

61 keys - Sequential Prophet 5, Oberheim OB-x, OB-Xa, ARP 2500, PPG 2.2/2.3

71 keys - Moog Polymoog