How to replace brushes on a makita 1902 planner..?

No, unfortunately this is brushes only come as part of the motor assembly Makita 6226DWE 3 8 Cordless Driver Drill Parts

Hello Derek, it seems that your motor or motor brushes have failed please contact the manufacture about replacing the motor brushes.

Try pulling out the brushes and blow some air in were the brushes go it may have gotten some trash in between the brush and the armature . they may need to be replaced, here is a pleace that will give you a breakdown and sell you the parts. http://www.ereplacementparts.com/makita-hr3851-rotary-hammer-parts-c-97_380_491.html

replace brushes

Brushes arc for several reasons. If the spring over heated and lost its tension or the copper line from the brush to the cap broke/burnt off or the brush wore down too far to be pressed on the armature properly. The replacement brushes you need are Makita part number CB-124. If you still have exessive sparking after replacing the brushes you may have a bad commutator on the armature. The only way to fix that is to replace the armature, Makita part number 512831-0.

check inside for any loose connections plus check the brushes. if like you say it is smoking it could be a trip to the wheelie bin for that one.

The brushes for that grinder are Makita Part #194074-2. They can be found on sites like www.ereplacementparts.com.

Hello. You are going to have to get inside to do a thorough inspection followed by a test run. Begin by unplugging it and then removing the blades. Check the play in the drum, and the clearances to be sure that the drum is still centered. It could be that a bearing has gone bad. If the drum still rotates freely, plug it back in and see if it operates smoothly, without sparks. If it does, take a close look at the blades as they are actually thin and delicate and can be easily warped. Joe

http://www.toolpartsdirect.com/cgi-bin/schematic.cgi/makita/1902
I've had really good luck with Tool Parts Direct. They send emails when something ships and are upfront about the parts they order direct from the manufacturer.
Part Number 225071-8 is $10.79 and ships in 10-14 business days.

Stripped gear in the feed mechanism? Use another, thinner board to help feed the wood evenly as a stopgap measure.