I am building a line-following robot using two of these motors:
I had everything on the breadboard and it worked fine - including both motors. Then I built the circuit, soldered wires to the motor terminals, added molex connectors, and one motor doesn't work. I switched the motors in the circuit - same one works, same one doesn't. I stripped off the heatshrink tubing, and connected the bad motor directly to a battery with alligator clips - it still doesn't work.
I am still learning to solder - could I have applied too much heat and melted something important inside my motor? Is there a way to find out?
Moving forward, is it a good idea to solder directly to motor terminals? Should I have used a heatsink clip?