What seller did you get it from bro?
I got my last one from Minginternational and the guy is riding it back and forth to work 10 miles each way for over a month now,low vibration,,no problems,,that motor was smooth right off the bat also...
I see the luckyearlybird kit is here today for the huffy 26" that I paid $10 for..well let ya know how she runs,,should have it done by Sat...that Grubee motor I got with the Trek runs smooth,,but it has way less torque than the ebay kits I've done..I have to pedal some up the big hills,,not with the LYB kits though
Good times...
Tom