Clutch Pedal Not Returning

I think this is common but maybe not. The clutch pedal does not come back to its original position on my 1970 Dart Swinger. It had this same problem awhile ago and I replaced the nylon bushings in the Z-bar and it went away for awhile. Now I have the same problem again. The bushings were NOS Mopar. First question, are the bushings the root of the problem? Second question, are aftermarket bushings any better than OEM?