Product review (5 stars): Perfect for easy fix... no fitting required, read below!
Some folks say they have to file on the bushings to get them to fit. In many cases, the original bushing was all plastic and those were fit so they could push on/pull off fairly easily.  These newer ones need to be seated properly on the shaft.  Filing may work to make them fit on easier but what I do is use a socket that is bigger than the motor shaft along with an extension. I then use this along with a small hammer with light taps to seat the bushings in place on the motor shaft and transmission shaft. Make sure to seat the bushings far enough on the shaft, otherwise when the transmission and motor are mated back up there may be some tension getting them together. If this is put in service with the pressure pushing the shafts then the bearings will fail prematurely. So, after it is all assembled, I always turn the coupling (motor and transmission shafts) by hand. It should turn fairly easily. I hope this helps!