I got the cab up fare enough to work on it. It is bad. I freed up the kill cable and pulled the passenger side valve cover. 2 injecters were stuck i pulled them and heated them to about 200 and taped on them to free them. I pulled the other valve cover and all 3 were stuck. The front cylinder back bridge had so much slack between the rocker about a 1/4"that it was side ways and its not the valves. then i could see the plunger on that cylinder had been rotating the bottom were the pin keeps it from turning or comeing out had broken some time ago.Its funny but i bet the last time i had it started years ago it was like this because it was only driven 25 miles after that. I planed to start it and sell but now?
This, boys and girls is why we don't let 2 stroke Detroits sit.
Doug, your bridge that turned is because the valves are stuck. It doesn't look like it because the piston taps them back up, spray the crap out of the stems with PB blaster and tap the top with a small hammer and a hard plastic rod to free them up.
I've unstuck many Detroits that stuck injectors and valves from sitting, never pulled an injector. Again, PB blaster and the nylon rod. Spray it on the plunger and rack and tap.
The broken retainer pin may require replacing that injector and it's a good possibility that's a result of a stuck plunger that popped loose while cranking.