Hello everyone, new around here. I'm desperate for advice. I just purchased a late 2000s model LA145 lawn tractor. Engine looks and runs great. I hopped on it to cut our grass for the first time and in the front yard it did great. Blazed through it no problem..once I got to the back yard where we have a pretty steep grade it simply stopped going uphill. I did the first few passes but the longer I cut, the less it would go uphill until it completely stopped. The guy I bought the tractor from said he got it from a guy who had gotten in too bad of health to mow his own place anymore so chances are it sat for a while unused. The guy I got it from buys tractors like that, tunes them up and flips them.
From my research, I've narrowed it down to a few things and I could use some advice on if I'm going in the wrong direction.
1. Drive belt wearing out and getting loose the more I run the machine.
2. Transmission tension spring getting loose
3. Transmission fluid either A. gunked up B. breaking down after heating up from the tractor sitting for an unknown amount of time.
After it wouldn't go uphill, I cut it off and let it sit for awhile. Went out about an hour later, cranked it up and it drove uphill (slowly) but I got it back to the garage.