Hey, guys!

I got called to a Gradall 534C-6 which all of a sudden won't drive forwards or in reverse. It starts fine and the hydraulics work. The wiring is a bird's nest, and the machine has had minimum upkeep over the past 15 years, to the point that straight sludge is coming out of the front differential and the transmission has what appears to be muddy water in it. I get 12.5 volts to the drive solenoids that hook into the hydrostatic motor, and the solenoid block works/is clean (I took it apart, cleaned it, and tested it with independent voltage).

I'm utterly bewildered and confused by the goings-on of this machine. It's almost entirely mechanical, with minimum wiring and (apparently) no fuse block. Does anybody have any experience on these machines, or have you guys seen or heard of anything like this? Any help would be appreciated.

Thanks, hope to hear from y'all soon!