The air piston is still available from Revox for $115!! Find a used 'Tape Tension Assembly' from a PR99 tape machine, and it uses the same air damper. The early bellows can be replaced with the later air piston and is a Service Bulletin upgrade.

If a later B790/B795 and ALL B791s, the damper assembly is an 'air piston' that can have its base rotated (very subtle) to influence its resistance and hence lowering speed. If the TT is an original B790/early B795, then that unit is a bellows that can't be adjusted. The Linatrak arm's up/down 'mechanical' movement is solely controlled by the piston/damper assembly.