[The biggest problem you will have is "quartering", making sure that each driver is ---exactly---90 degrees opposite its mate. There is no room for fudging, take my word for it.
/QUOTE]
Wheel pulling and installing is a little beyond basic train repair. On the O gauge 6 wheel drive motors, I took one axle out to gain access to the armature. The wheel I pulled took minor damage. OK for my use but I couldn't do it to something with a high quality. To replace it I had to have the drive wheel right on the exact gear tooth to line up . Not to mention the other side being aligned and then pressing the two together. I did it slowly, rechecking the alignment often.
I got it together , it ran until the drum broke on the e unit. The short fried the armature.

hwell:
I'll get around to it but I'm not looking forward to replacing the wheel.
I thought the alignment deserved another mentioning.