I pulled my old Mindstorms NXT out of storage (it's been there for a few years). After patching together a test robot, I noticed that my motors behave strangely.
At first, one of the motors did not respond to move commands. After disconnecting/connecting a few cables, another motor stopped working (with a different cable, on a different port). While troubleshooting, the behaviour erraticaly switched between all three motors working (rarely and for a brief time), two not working, or one not working.
Now it's stable, with one of the motors not working, always the same one, no matter what port I plug it in. I suspect that it may be faulty, however I'm not sure due to the strange behaviour described above.
Does anybody know how I can test the motors, see which are faulty, if any? Or any other tips troubleshooting this? Thanks.