hello joe! first, try to change the plugs between the solenoids on top of the pump. and you can test the angle sensor too, just unplug the two solenoids, then let the machine run at slow speed few minutes. you can hear when the pump reaches full swash. then plug a voltmeter + to the anglesensors middle wire, i remember it was black. then the - to the ground. you should see there 4,30volts. i saw in our excavator, that this was ok when motor was cold. after it gets warm, the a-sensor started to give very unstable power, like in a 30 seconds it went from 0 to 5 volts.
i ordered an a-sensor from china, the first one went broke in a few ours, but i got new one from the seller, didnt have to even send the broken one back. now it has been working.
if you have to change the solenoids and order them from china, you should first get it to parts and clean them up well. in my solenoids, i just plugged them and found out them sticking. i cleaned them up, and found there a very small metal particles which was left there after the machining. just take it parts, and flush well with brake cleaner or something else. after that they worket as new. it is not really so hard to find out how does the hydraulics work, only if you have problems with the wiring it gets ugly. or so i think, i dont like electric works