Our early production 4500 is back to life and running on all 3 cylinders, It came to live with us about 10 years ago, the previous owner couldn't get it started any longer, he said it just got harder and harder to start. We pulled it with another tractor and it fired, but only on 2 cylinders, some times only 1 . I finally got time to pull it apart, it had big chunk missing out of one exhaust valve and the seat was pretty bad on another. Replaced the 2 bad seat inserts, the other one ground clean so I left it, 3 new vales and it is back together, the bottom end had been done and the bearings are tight, so i just did the exhaust valves, (Thanks to missouri massey man for the bolt sequence and torque specs) I put it back together and couldn't get it to bleed right, so we pull started it, it fired and cleaned up pretty well. We put the back hoe attachment back on it , it got removed because of an oil leak, which turned out to be a cracked line, I welded the crack up and it seems to be going to hold, my son dug a fairly long trench with it this afternoon. I will try to post some pics of it soon.