Case 580b Injector problems

I need some advice about a recent problem with my backhoe its around late 60"S 580 construction king with a 188 engine I believe. It was missing a little so I added seafoam to see if it was a injector problem. About 20 min into running it made a strange noise and started running worse and black smoke came out and the rear cyl started leaking diesel out if the exhaust port. I pulled the injector out and the tip of the needle was broken off, I then pulled the injector apart and the needle had a slight bend close to the end. I ordered a rebuilt injector from Ebay from shop seller. It all looked good except the top side for the return line had a different adjusting style than mine, otherwise looked the same. I installed and still not any better. I bled out the line and still no help. I the switched the inj with the next cyl to see if problem followed the inj. when I crack the line it seems that its has foam as if it has air. I continued to do that for both cyls and is seemed to help a little. I was getting white smoke and seemed like it was getting better, but still lacked power. I tried using it and when I put it under a load it lacked in power and black smoke was coming out and it the temp started running too high. I hope I haven't lost a cyl, any advice. Thanks in advance for any help. Doug