another little gem i'm sure you're all aware of:-
transparent cello tape (scotch tape) over the optical "eye". initial eyeball mk1 inspection can easily miss it, but there is enough I/R reflection off the adhesive side to blind the pickup sensor rendering the mouse cursor motionless.
also one or two stray cat hairs in the sensor hole (or substitute as necessary), also renders an optical mouse non functional.
had a PHB fall for the tape variant and reboot his machine as it "must have crashed, losing a couple of days of work" apparently. God knows how much work he lost every weekend and had to re-do on Monday when the machines all got a scripted restart on Sunday night.
A lot of serial mouse connectors had locking bolts and cable strain relief built into the plug. None of this "falls apart after a year" apple connector rubbish. IIRC those aluminium mouse pads flew beautifully spinning in a long lazy cork-screw arc. usually to end up sticking in the plasterboard walls. RIP proper built kit (Sun/Sgi etc.).