Joe,
If you have roll pins, there may lie your problem. They will break prematurely. They can shear off and leave the end pieces in the lift levers, making it look like they are ok.
If you have roll pins in there, replace them with spirol/spring pins. These are much much stronger and will last a long time.
P.S. A set of roll pin punches will greatly help you in removing and installing these pins. They are worth their weight in gold.
