Where in Mich are you? I get mine from Burnips Equitment , Dorr Mich. They also have a store in Big Rapids. I havn't had to get any in a long while so I am not sure if they can still get them. Ask for Dave Smith in parts
They use to be an Oliver dealer and they get there parts from AGCO. But what I found out when I moved out of that area is not all AGCO dealers can get parts for these tractors. I used to know Dave so I just order from them if I need anything. I live up by Houghton lake