You can replace the bearings and it is not that hard to do. You first need to get the endbell off. The endbell has epoxy on it, I found is easy to get off by runing the motor to get it hot, then take out the screws that hold the end caps on and tap the output shaft on a piece of wood or something to loosen the epoxy. Mine came apart with fairly little effort. The bearings may be epoxied in but mine came out easy with no damage to anything. I used a phillips head screw driver that was bigger than ID of the bearings to push them out. The bearings you want to replace them with are 5mm ID x 11mm OD x 5mm W. I used these
http://www.bocabearings.com/main1.as...85C-2YS_#5_NB2, but cheaper ones will work as well. My 4600 made it about 50 packs before the stock bearing went out, it now has about 200 packs on it. It seems the stock bearing are not very good so why buy a new motor only to deal with the same issues again. Its deffinately worth doing. Good luck.