I have a 2001 773G with around 400 hours on it and I can't get the auxiliaries to work with a new grapple bucket. I don't think the variable flow has ever been used before but the constant flow has always worked fine with my brush hog and if I pull the right front trigger the bucket will open but the variable thumb switch on the back does nothig. The variable flow LED on the control panel lights up after pushing the button once. So far I've- Replaced the right joystick switch cluster because the other switches were sticking. Tested the aux coils, both read around 3.5-4 ohms. Removed and cleaned the auxiliary stem valves, both seem to move just fine. Tested the new bucket on my neighbors machine and the grapple works just fine. Checked every fuse and inspected every accessible part of the harness for mouse damage. I'm currently stuck and was hoping to have it ready this week to help a friend clear a site for his new house so I appreciate any help or advice you might have.
400 hours over 24 years? That machine has sat a lot. I'd start looking for wires chewed up or you may have a sticking valve.