The first thing to check is that there is nothing rubbing against the basket when it's spinning. That would account for the appearance of struggling. Is it a jerky motion or smooth?
If nothing is rubbing against it, swap the entire reel mech with another position and see if the problem follows. If it does, then it may be the motor.
I had a motor before that was worn down in that it spun fine but when it stopped, it skipped to the next symbol on the reel instead of the one it's supposed to stop at. Is that what's happening here? Or are you getting just a completely wrong symbol? Does the problem correct itself when you open and close the door (the reel realign properly)?