Looking for help diagnosing problem

Hello all,
I have a 125C International Power Shift (picture at work) which I use for a 10-40 hours a year clearing land for my apple orchard.
The issue is that it will not move easily for about the first 15 minutes. It moves very slow at first, then slowly improves until it works great. However at times it will stop moving. When it stops moving, while in gear, if you decelerate and then accelerate it does nothing, but if you leave the throttle alone and put the trans in...

Looking for help diagnosing problem

Looking for help diagnosing problem