“gobs of epoxy” shouldn’t slow the motor down unless rubbing on stationary parts. might very slightly affect the spin up time, but prob not noticeable. The other option to epoxy balancing is by machining the stacks, which can affect the uniformity of the magnetic fields.. but either way a balanced arm is better than an unbalanced one.
The enamel is prob better sanded off at the contact points, to give a a cleaner solder joint.
