Actually it's probably more electrical. I have a 6" Craftsman joiner planer that my Dad bought years ago. He hardly ever used it and it's been in storage all this time. I tried to get it set up and running but the motor seems to be weak, slow to turn and all. What do I need to do to get the motor working properly? New brushes? I'll understand if this gets pulled. It looks similar to this model with motor mounted below and belt drive.
(http://images.craigslist.org/01020801041001031120070918f53bce5f00e76b1a9200cd74.jpg)
First you have to determine what the problem is. Start by taking the belt off. (power off)
Then rotate the pully by hand on the motor . Tight? OK? Then try turning the pully on the planer too tight, maybe the bearings rusted up? those are the things your looking for. If the motor spins freely, plug it in and run it with out the planer to check it out.
If the motor is Ok then you have to help out the bearing etc on the planer.
Ron
Try blowing it out with your air gun. Mine gets lot of saw dust in it and completely stops working. Once I blow it out real good it is back on line and working fine.
Unless this has a bridge rectifier and motor control this is an A/C unit and does not have brushes. There may be a start or run capacitor that is causing the problem but like others stated could be a bearing issue. What does the nameplate on the motor say? and what voltage?