This Speed Gems Diamond 12x2 motor looks like it might have caught fire. I've had a couple of armatures with rough comms clean up nicely with some comm lathe resurfacing. This one will be interesting to find out how extensive the damage is.
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After a few light skims, the comm while spinning was starting to look like there is still some usable copper, but with some dark area. Stopping to look the area over shows that there are large patches with no copper remaining. No more cleanup planned for this armature. The red stripe was my mark to know where along the length to stop cutting. No red left = stop cutting
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Borrowing this pic from Elkcycles...

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Frankensteined RC10T3 / Franky Jr RC10GT-e (x2) / A+ stamp / Toy Story RC / Graphite replica / B1.5 BFG 5LTi / Clonewald / Hyper Hornet
"I love the effort, but it sure looks like you took the long way around to a tub again"