Yup all part of the hobby. I've been learning more than ever on this tractor and it was running fine not too long ago so figure it can't be anything too serious.I feel your frustration, don't let it get to ya, believe me that's part of collecting old tractors. Currently I am working on my 50 that started running rough. When I opened its oil bath air cleaner it had several mice in various stages of decomposition in the cup. Usually I just find nuts and once had one pretty much filled with shelled corn. Now I am waiting on the carb to come back and the cylinder head to get done. Hopefully it will run great once all that is done otherwise I will have spent a lot of money and not resolved the problem, believe me I have been there before.