On my tractor (old ferguson 35) the three point cylinder only holds about a pint of fluid.... out of about seven gallons in the tranny so I dont really worry about it. You wouldnt notice a difference on the stick one way or the other.Do you check it when the 3pts up or down??
It sounds more like a problem with either your control valve, or you may have an internal leak going on. When the fluid is cold everything works fine, but after a few bales and the fluid gets hot and thins out.... you lose pressure to operate the cylinder. What color is your tractor?Well ive cleaned out the 2 valves in it twice to get it running. It runs, does around 3 or so bales then wont raise up. I thought it might be los on trans even tho it is just right when the 3pt is down.
seriously you need to get hold of a pressure gauge and find out if/where you are losing pressure. If your dipstick shows full even with the lift up your system should function properly. On my fergusons there is a side plate that I can remove (the dipstick runs through it) and watch whats going on inside. When the system is running right the oil will be relatively smooth on top. If there is a leak somewhere you can see it plainly if its above the oil, or if its leaking below the oil you can see the oil swirling as soon as you engage the pump.Ill swap it next hay season. Have to give it away now. lol. Likely cant afford a JD