Help diagnosing wiper motor speed issue-1978 280z

I also found that disassembling the whole linkage, cleaning, using emery paper on bushings and shafts, grease, all made a big improvement. For me, prior to rebuilding it was hard to even rotate the ends that connect to the wiper arms.If your rubber pieces that surround joints are deteriorated, you can buy from 240z Rubber Parts. I even purchased some felt to cut new felt bushings for the joints; battery terminal felt sort of works but I found to be too big.

http://www.240zrubberparts.com/