The tracks were the most difficult part of the "Thing". I recall that the track bolts were a SOB to get loose. The sand and dirt wore down the head to where a normal 12 point socket would not work. I recall us having friends and family send us 6 point sockets. We spent many,many hours with the bolts and the sorry.track jack. The worse memory I can recall is to have a track broken in a deep rice paddy. Then have to pull the Ontos and its track dragged out by an Amtrac (tracked amphibious vehicle). (this ordeal) was followed by many hours of trying to pull the vehicle back onto the track. Works good on concrete with one Ontos pulling the vehicle and another holding the track. Try it in sand and you will need another to pull and a lot of luck.
Parts were what you cannibalized from others. I also remember one other area of problems with the Ontos. It was the armor plate bolts. I guess someone thought that using fine threads on the bolts was a good idea. Yeah right, with dirt and sand, it was often the case that no more than the four bolts could be installed. This to me was of great concern. The Ontos, as with all vehicles, were the constant target of the clever VC mine. I spent much time riding on the top (sitting on the round pipe that held the 30 cal MG). Most of the time thinking of being blown off the vehicle then have that dammed armor plate land on me. Mines took 4 of 5 vehicles during my 13 months.
Mr. Blanchard reminded me that the Ontos crews had more weapon cleaning than any other crew served weapon. The three man crew had to clean six 106-mm recoilless rifles, four 50 caliber spotting rifles, one 30 caliber machine gun, one 45 caliber submachine gun as well as clean their personally issued 45 caliber pistols and whatever unofficial weapons they may have carried.