If the motor has ball bearings they are quite easy to replace. First of all take a sharpie and mark the position of each end cap relative to the center housing--put one mark on the end caps on one end, and two marks on the end cap on the other end. Make sure each mark also goes onto the center housing so you can "clock" the end caps exactly the same as they were. Now remove the nuts from the 4 long bolts that hold the end caps on and pull the bolts out. Put the nuts back on the bolts to keep them safe. Some end caps just about fall off and some need a little prying, but they will come apart. Note the bearing numbers, go to a bearing store and get new ones. There are various kinds of windings varnish--I've used Glyptol before to paint onto any dicey looking windings, but if everything looks good, I'll just put it back together with no varnish. If the centrifugal points look badly burned you can clean them up with emery paper. Then just put the bearings back into each end cap and carefully put it all back together. Did I leave anything out?
