Dad had one, but he got rid of it in 1988. Learned to use a round baler with that old baler, but don't remember much about it. There's a user on here by the name of ironpeddler, I'd suggest sending him a pm.
Your adjustment is in the length of your belts. Keep them tight and you'll make tighter bales (says the rancher who ran with a sloppy center belt and slack outer ones all summer). :cowboy:
They are a pretty simple machine. Ours was new in '72 and picked it up from an uncle used in '74. About 25-30,000 bales through it and still hums along. Bent the pick-up on it this year though...still made 450 bales.