Borrowing my dads skidsteer and possibly buying it but don't want to use it before fixing some issues. It's a 2000 (might be a 1999) Case 75XT The worst is the right joystick doesn't spring back to neutral and if you don't hold it to neutral position as soon as you drop the safety lever it will operate at full speed. When operating machine joystick functions pretty much normal though. Assuming some kind of spring is gone? Another issue is when cold sometimes the brake won't release, always releases after idling for a bit and generally only an issue in the cold. Assuming it's probably a sensor on the arms? But it's odd that the brake releases fine after, it's been happening for a couple years and hasn't changed. Last one is as soon as machine is started overheating alarm goes on and stays on. Assuming the sensor is the only possible cause?
What oil do you have in the hydraulics? It called for 10-30 I believe, but in your climate they may have speced something even lighter. You might try draining the hyd oil and put 10-30 in it and see if it releases the way it should. The joystick likely does have a spring in it that has failed. I have had 5 XT machines starting in 1999. I never took a joystick apart. Case dealer may have a break down of the joystick and you could see how its built. I would agree that the overheating alarm is due to a bad sensor.
It has 10w30 in the hydraulics. They've had some play for awhile as it has 9000 hours, but one day just completely went.