Well Forest, stupid is as stupid does!!!
1)That pedal you are calling a clutch is just a dump valve. It is not to be used to shift. The hydro will still turn the transmission in neutral enough to not get it to shift.
2) NEVER move a combine with grain in the bin. I believe you will find several stickers telling you this and pages in the operators manual. That 60 bushels of grain added 3500 lbs to the total weight of the machine.
3) FIX the brakes!!!! You would not take a car/truck on the road without brake but a 15,000 lbs combine is OK with no brakes???
4) The hydro stalling is just dumping a pressure relief valve. You could set there for a long time and not hurt anything. Leave the combine at full engine speed and pull back on the control handle. Many times you will be able to go on. Even if not this is not a panic time deal. The hydro will hold it there. So back down the grade. You have control of the machine then. NEVER try to shift a combine of any kind while moving. Plus the MF 750 shifter is a PIA at the best of times. When you lower the engine speed you loose pressure in the hydro. Learn to leave it at speed. This is why many of the new combines are either at idle or wide open too many people idling them around and tearing things up.
4) Always go to a lower gear BEFORE a steep grade. I have several hills that my JD 6620 or JD 7720 will not pull in 4th/road gear. I stop at the bottom and shift to third and away we go.
What is it going to cost you for the pole repair?? My Dad turned a corner to short with a trailer a few years ago. He hooked the brace wire to a electric pole. He dropped the pole that had a transformer on it. It cost his insurance company about 30K to pay the electric company for the damage. Then his insurance company dropped him. His new company charged him double for several years.