Yeah, all those little hoses going to the spool caps are servo or pilot, but we're past that now.
Now you say only R travel works properly. That sucks. Something must be bleeding oil back to tank. I think you'll need gauges. A pair with 7k psi should be plenty. You want to see discrepancies between pumps, what functions yield correct pressure. You'll also need to find cycle times for your machine. We have to start at the beginning and work through. Otherwise, you're wasting money on parts and labor for nothing. You stated that you have the factory service manual. That's a big plus.
If you wanna tackle this, myself and others will help you along. I will preach safety a lot. I mean no offense, I just don't know your skill and comfort level. I don't want anyone getting hurt following my instructions.