I own a 1966 Twinco and had a generator bolt shear due to corrosion. The left one is from the good engine (not sure if it is also corroded) and the right one is the failed bolt. It sheared twice, the second time is caused damage to my spinner and mounts due to vibration. (the hole in the middle of the corroded sections was how I extracted it from the universal mounting block).
IF you use a universal mounting block (brass with multiple holes) to mount the generator, use caution that the threads are exposed to one of the holes and water can corrode the bolt, causing failure, vibrations and potential spinner failure.
Anyone else have this kind of issue?
Steve