I am trying to help out a buddy who shut his ’68 4020 down after the transfer pump (fuel bowl style) was so clogged that it would barely run. He cleaned the screen and put the bowl back on and now it will not start. Here is where I get into the mix, I bleed the system starting at the filters, then at the inlet to the injection pump. So I then cracked the lines at the injectors but don’t get any fuel. I believe it has a JDB pump and when I crack the bolt on the right hand side it will start and run, but when I tighten it, the tractor shuts down. What am I screwing up???? Where are the bleed screws on the pump? Your help is much appreciated! Matt