Thanks VERY much for the link to the other thread!! I searched originally when I had my issue, but he posted his after I had started this and I didn't do another search, not sure I would have found it if you guys hadn't posted here!!!
I posted the results on the other thread, but I will close the loop here and finish this. The tiny filter screen on the inlet was the problem. I cleaned it and it works as good as new!
The filter screen is under the inlet port circled in red:
The spring and the filter screen were down in the injector pump housing:
It was a little tricky to get them out. I used a tweezers for the spring and then a wood screw for the filter. Put the screw down inside the filter and pressed it to the side and pulled it out. I'm sure there is a better tool for the job, but it worked.
The filter screen itself is tiny! The size of an eraser head on the end of a pencil. Mine was dirty.
Now it is clean!!
As soon as I got it repaired (it took about 30 minutes start to finish) I disced 5 acres of damp soil and it worked great for the hour and a half that it took me.
Thank you VERY much for figuring this out and reporting it here!!! This saved me hauling my tractor to a different repair shop at a minimum and possibly $2,000+ to replace the injection pump which is what the mechanic that had been working on it was telling me the problem was.
Thanks!!!!