shimming brushes & faking rubber mounts
In Monticello Utah (I think it was) about 20 years ago my early 80's R100RT gave up the ghost after running increasingly badly. It turns out the brushes in the alternator were so worn that they barely made contact with the armature (I think it might be called the armature) My buddy and I shimmed them up with a wooden match stick so that the spring could force enough contact to make decent electrical contact. Also all but one of the rubber mounts that hold the diode board had sheared and it was shorting out against the case. We suspended the diode board on wire ties which we held in place by squishing them between the case and the cover. The bike made it all the way back to San Francisco like this.