Hi guys, today I finally opened up my N900 to do the fix-it-before-it's-too-late soldering to the usb port and I was able to fix the vibration issue, too.
I had already tried both scripts described in this thread but they didn't work.
Today I switched on the phone while the case was still open (holding the battery in place with my hand!) and the pcb exposed. I ran the script described here while manually rotating motor's eccentric and after some manual turns it started spinning!
Hope this may help someone else!