Wow. Thanks Owen. I was excited when I found one of the cables had a grease fitting on it. It seemed to help a lot for a while. Lost motion may well be my problem. I stood there at lunch today and stared at the problem for a while... I am thinking a couple of ropes - one running up so I can raise and another running down so I can lower - should be possible. That way I can be under the truck and move the lever in both directions. Maybe I can try that soon. This weekend is supposed to bring rain here so it may be a couple of days before I can report back.
THANKS for the idea! Thinking about it, I remember "lost motion" problems with throttle cables on boom trucks. Getting it tied down correctly solved those. Maybe it will fix this too - and for all I know - when I do that I may find that the jacket and cable are frozen. My M936 came out of Ohio, and I imagine they have TDG (Truck Destroyer, Granular) too