I had my mouse go bad on my old Amsterdam 1512C. It sucked because it used non standard ports for everything, keyboard, mouse, monitor... In order for me to fix the mouse to get Gem Desktop working again, I needed to solder the connection back together again.
I also had a really cheap $15.00 mouse on my 486 that had issues too. It used metal contact so they got bent out of place, I tried bending it back to normal, but it never quite worked the same.
My Sun Sparc Ultra 10, mouse (went to mechanical mouse, after a stint of optical mouse that needed a special mouse pad) Had some problem after 3 months. I got a replacement and it seemed to work fine after that.
After that I moved to optical mice/track pads.