I'm restoring my 1940 john deere model A with electric start. I got the generator rebuilt and I'm installing the generator bracket, once I got it all together I noticed the generator will shake once and a while when the tractor is running. The pullys are closely lined up. I took the belt off and the generator bracket still shakes. So I'm assuming it just does that. Should I be concerned? It's mounted to the fan shaft mount, unlike on my 1941 where someone mounted it to the frame. It is also a 12 volt generator so I had to shim the original mounts to line up the pullies. At least it charges good.