What exactly would be worn to cause this? I doubt i tear into it, but kinda curious about it. Only does it under load, both low and high range affected in the 2nd/4rth postion. Is this a common issue with this series tractor?
I can't say it's common because I don't have the many hours of operation under my belt to say so. But I can offer you a simple but hard truth. It's a problem that can only be solved by opening up the trans. You could one or more issues. Worn transmission shaft bearings, weak shifter detent springs, worn gear(s). The only way to tell is to remove the shifter tower and do some investigative inspection. Is yours the 4 or 6 speed trans?
Here's a few pics of the trans of my 60 which is currently getting an overhaul. The trans was the reason it was parked. It's all been gone through now.