All, I had a similar problem. All was looking well, I had good continuity so I tried shorting the negative and still nothing. I eventually measured the resistance across the motor and it was open. Tried wiring up to my makita battery and nothing. Guessed it might have some kind of protection. So next step was straight to a 9v battery a few time taping and it jumped once with some help. I had to spin the motor about 10 times and now it works fine.