My MTD riding mower (model 135M679G062 14HP 42" cut) will sometimes crank, sometimes not.

The battery and the starter are good. I had them checked by a technician. I called him because it would not crank at all. He started it right up. I asked him what he did that I did not do. He wasn't sure.

After he left, I started the tractor, ran it for over an hour. I stopped and started it several times but left it running most of the time to make sure the battery would stay charged. Then I tried to start once more and got nothing. It would not crank.

I pushed it to get near an electrical outlet in case it was the battery. The battery was OK. I was stumped. Then, for some reason I decided to give it one more try, and it started!

While it was running I put it in the gear position that allows me to get off the seat without killing the engine. However, once I got off the seat it died. This had never happened before.

I remembered then, that I had gotten off the seat earlier to talk with my neighbor and could hear the mower engine faltering but just managing to keep running. I remember thinking that it was getting low on gas, but it was not that.

Please tell me what could be the problem, and how to check it and fix it. Thank you.

Sound to me the like the safety ground to the seats contacts are bad. It should not run in gear and shut off.

When you got off the first time there was possibly enough intermittent ground there to barely keep the mower running

Check that ground contact from frame to seat system and that's probably the problem here. It would explain the scenario. Clean the metal contacts or the bottom of the seat springs that ground to frame.

The tech should have went over that with you as a possibility.