We bought it used a couple years ago. I'm not sure about the battery condition, but within 7 months we had to add 8 gallons of water. When we first got it we didn't put water in it for over a year and it just stopped, so we got water put in it then, and it seemed to be fine. Do you think the battery in damaged now?

but when the up and down doesn't work the drive will or vice versa? So he don't think it could be the peddle sensor

If it was a battery issue I'm sure your mechanic would have picked it up,
running that long without water would definately have caused some battery damage, but enough to cause your problem-unknown
I would be testing/replacing the STS
The switch on the right pedal supplies power to hydraulics and drive
I would be suspecting switches with voltage drop under load

We bought it used a couple years ago. I'm not sure about the battery condition, but within 7 months we had to add 8 gallons of water. When we first got it we didn't put water in it for over a year and it just stopped, so we got water put in it then, and it seemed to be fine. Do you think the battery in damaged now?

Sounds like a thermal sensor issue,you say it does it when it gets hot What condition is the battery in?