ford 755B backhoe

I have a 1988 Ford 755B that was running great. I was doing work along my driveway and shut it off. Ten minutes later I went to start it again it sounded like a loose battery cable, that snap of a spark. I tried it several times to start it, nothing. The solenoid for the glow plug still clicked. I thought something was wrong with the starter so I removed it and took it apart; it looked in great shape. A few hours later I put it back on it started right up but was missing on one cylinder. I had to run it that way until I could get my driveway passable. I found by loosening each of the injector lines one at a time while it was running that it wasn't running on the rear cylinder. I put a new/reconditioned injector in and it still isn't running on the rear cylinder. I wonder now if it set up when I shut it off and had time to cool off and freed up but had damaged the engine. The fluid levels are fine and the weather was in the mid 70's. Is there something I may have done wrong when putting the injector in? When I loosen the line to that injector it seems to be getting fuel, at least to the injector. Not sure what to do next. Any ideas, HELP! Thanks

ford 755B backhoe