This is an idea I had when mine went out, but didn't follow up on. Having gotten back into R/C and monkeyed around with electric motors a bit it's come back to me - why not just replace the motor? Unfortunately I can't find my old module to see what size motor was in it, but looking at the above pic, it appears to be a 370, which you can get for less than $7 - Link
The brass gears that come on these things can be crushed off with pliers. The trick is going to be prying the worm gear off the old motor and pressing it on the new one. Then you just have to wire the new motor in.
These modules aren't going to get any cheaper or easier to come by, so I thought I'd throw this out as an alternative to replacement. The can-type brushed motors will always be available.