Sounds to me you have a leaking internal seal on one of your drive motors which is filling up your chain case with hydraulic oil ,and there s no oil in the tank and thats way nothing hydraulic is working , there is a plug on the front of the machine about 8inches off the ground , consider it a rear axle plug , when you take the plug out on level ground the oil ( 10-30, 10-40, 15-40) level should be right at the bottom of the threaded hole , if it's over full it is probally the seal of the drive motor , sometimes though water will get in the chain case and float the oil level up higher than the plug , if you are losing hydraulic oil and don't see any leaks it is filling up the case which holds a lot over full , when the chan case is full it will start leaking fron the vent plug on the case cover and the gaskets of the 3 covers that cover the chain case , not too bad a job to repair