回答“How do I replace the engine shut off switch?”No, you don’t need to remove the injection pump (IP) or oil filter housing. Indeed, doing so would be a major task. You can unbolt the plastic VCV on top of the injection pump and swing it out of the way for a better view, but not required. There are 4 bolts which take a 10 mm wrench. A ratcheting box wrench will make the job much faster. There isn’t enough room for a socket wrench, as I recall. A trick in removing and installing the shutdown valve is to angle its body towards the engine block since there is a smidgen more room on that side to clear the filter housing. It also helps to suck in the stem w/ a hand vacuum pump, but that might not be possible when the diaphragm is torn. Otherwise, push in the stem with your finger. Yes, it is important how you insert the new shutdown valve into the IP. The vacuum port should be up. The L tip must go past a flat lever, so that it can pull backwards on the lever (can’t see it, but imagine). That lever is closer to the engine block. If angling the shutdown valve...