The only time mine gets to "rumbling" is when I'm pushing a 2 X 12 through it. It still has less vibration than any other machine in its class. I do so much with thick lumber - it is a little odd for me to do tiny projects. I am working on a lot smaller stuff right now - ornaments, jewelry boxes and the like - I have a display going into a salon for consignment. Thin wood feels a little weird to me. It is a lot easier.
There is a circuit board in the back under the black strip that runs down the center of the back of the saw. It has a lifetime warranty, so they should send him whatever he needs. I had a problem with my speed control a while back and after trouble shooting it over the phone - they sent me everything it might be - speed control, circuit board and even a new motor. (at that point I was cutting everything at full speed because it wouldn't go any slower). They are a great company to do business with.