Well, I found the inspection port on the brake side of the bell housing where I was told it should be. The rubber plug is really decayed so I hope I can order another. I was not able to look into the port because the tractor has a Bulldog front loader bolted on and it blocks line of sight into the inspection port.
So here is my evil plan: my son will bring back my endoscope and I will affix a small diameter vinyl tube to the 'scope. I will then try to maneuver the 'scope to the offending rusted splines on the input shaft. Then I will try to squeeze some oil, not very much, through the tube and onto the input shaft. Then I will try to rotate the shaft and apply more oil until the clutch is assured to slip. Or even better apply just enough oil for the friction disc to slide on the spline. I think this is not going to be easy. However, if it works it will surely be easier than splitting the tractor, especially since there's that pesky front loader bolted to the tractor that seems like it will really get in the way of splitting the thing.