(ET) Put a new tire on the E15

[Chris Zach <cz alembic crystel com>]

So now I can drive it. Problem I am noting though: The motor studs for 
the armature are getting hot. Which is bad. I checked the wires and they 
are good; however the studs feel "loose" and turn a bit by themselves.

How are the studs connected to the brushes inside, can one tighten them 
without opening the motor, or do I have to pull the motor?

Oh and can one put an E12 motor on an E15? I have one of those in the 
shed (the shunt wound E12 one) or would it need a different belt (it has 
one belt pulley, not two)

Chris