You can have the motor misaligned and test it, and it won't have to much bad effect, just fire 1 shot on semi and listen. If it needs adjusting, adjust it and fire once again.
It doesn't do that much harm to the gears.
Also, you could get a magnum or turbo set for about 300 shipped, which includes a motor, from
www.airsoftglobal.com or maybe other sites, I didn't look any farther than that.