Looking for some advice from those of you who are familiar with the 30 series powershift troubles and repairs. Have an 8730 tractor, 18 speed powershift. Last year I had a speed sensor malfunction (coded as h3 and h5). Tractor continued to work well only limitation was that it would not set the upper limit at 12th gear for forward starts and if I clutched when traveling in higher than 12th gear it would not automatically shift down to 12th. Had to be careful but no problem. This summer: pounding out the bales one afternoon, didn't realize I had a slow hydraulic leak in one of the baler lift cylinders. I gradually lost hydraulic oil each time I dumped a bale until I lost enough oil that my forward motion (f11) in the tractor ended. Thought it had slipped out of gear but further inspection showed oil right off the dipstick in transmission. Refilled with hydraul 56 & started baling. Had tractor stop a couple of times but then resumed normal operation. Here's the dilemma. It is now more and more often stopping forward motion / transmission shifts on its own to f7. I can regain movement and shift up normally but then it will shift out. Very annoying. Yesterday, ran tractor all day loading bales and it did this once. Today loading bales and after about an hour of work it started shifting out about once every fifteen minutes but then got worse and worse until I finally limped it back to the yard and parked it. Still throws error codes h3 and h5 but now also throwing code h1. As I stated earlier I can usually just resume motion and shift upwards but sometimes it will throw a code c12 and I cannot do anything until I turn off key and turn it on again. Did I cook my transmission? Could it be something as simple as blocked filters from the low oil flow (filters not changed in a while)? Is it more likely an electrical problem (not sure how since trouble started after low oil operation)? Should I overfill the transmission oil reservoir (can that do damage?)? Am I now the proud owner of a massive paper weight? Any help appreciated.