From time to time, I'll buy non-slot motors (usually modern Mabuchis, but sometimes others) for parts that can be used in the old motors. Not long ago I got a half dozen eBay motors because they're of a type that use an armature the same size as an FT36D. These particular ones I bought for the magnets as the modern ceramics are usually at least "Arco" strength. The arms are 5 pole, so I wouldn't normally use them and, at $5 a pop for the motors, each pair of magnets costing $5 (if I throw away the rest of the motor) is cost-effective. Of course, these magnets are a bit tall and too long, so they have to be cut down to fit them into a 36D can...but that's not that difficult and even without re-zapping, the magnets still come in at around 1000 on my meter.
This time, I took apart one of the motors and decided to strip and rewind the arm. The stack was way-long for a Mabuchi FT36D application, so I shortened that also. The com seems like a good quality piece, so I carefully took apart the tab welds and had at it. There are a couple of different 5-pole patterns I've thought about, so I used one for this along with some #29 wire and re-welded the com tabs. The result is about .3 ohm per pole with some variation because of the way the first and last poles get wrapped. Anyway, the motor runs very smooth and has a weird/different sound to it...probably because of the very narrow gaps between the poles. Lots of revs, drawing about 1.7 ohms and not getting too warm, but it doesn't seem to have much natural braking. I might tighten up the airgap some and see what that does, but it was a fun project.
Anyway, there are all kinds of electric motors out there that can be hacked for our purposes and they often go for peanuts as "surplus". They can make it a lot easier to work on "the old ones".