When I first start the tractor, and warm for about 5 minutes, I can press the pedal either forward or reverse (it has an instant reverse transmission) and hte tractor will engage quickly and powerfully in both directions.

After warmed up, or 20-30 minutes of running, the trans will gradually take longer and longer to engage when pressing on the pedal, until it will take forever to engage and I simply stop working and wait for the next day when the tractor is cool again.

I remember removing the oil sump screen thing at the base of the trans/rear hydrolics and it has two screen, one for each chamber, and a sump tube which goes to the trans front hydrolic pump that sucks in trans fluid from this two screen sump base thing and pushes the fluid into the clutch packs for movement. I remember the two screen resevoirs in the base had a couple passages between them where the oil could flow between the two reseviors, but someone had welded them closed to keep the oil separate.

I'm wondering if the problem I am having with the trans is:
1. With the sump welding separation and the oil is getting two hot and not working.
2. Something with the trans hydrolic pump, which I remember seeing some weld fixes on it when I replaced the clutches, but I thought since it would work when cold-warm, that may not be it. Also, most of my tractor useage was for only 30 minutes anyway, so I didn't worry about it, until recently when I've been needing longer useage and would like to try and fix this issue.
3. worn out torque converter which only rears it's ugly head when hot

After it is hot and I can finally get the tractor to go forward, it is still pretty powerfull and if I don't stop and just keep the pedal engaged, it relatively works fine...however, it does overheat and lose power on occasion when I am really running it, or when running it in the summer in 90 degree heat and with a big load of dirt on the scraper going up hill. I usually only run the tractor in the fall/winter/spring when air temps are 50-70 degrees F here in California Central Coast.

My neighbor suggested I put a giant trans oil radiator on it with more capacity and more cooling and see if that works, like retrofit something from the junkyard, only thing is, I'd like to save that as a last resort since it would be a bit of work to do that.

Thanks for any help.