volume control

I’m planning to swap out an 8300 Rite-temp valve that is currently roughed in from previous plumber. It was set up for shower head only with bottom port capped off. (Was told would not work for what I want to do) Have a K-11748-KS main valve with tub diverter and service stops - shower stall...

The set screw was well hidden on this one, but I found it and removed it. But now the lever still won't budge. I've decalcified as best I could and have even used WD-40. But it's stuck. Has anyone seen this model before? It would if I knew whether I should turn (counter-clockwise) or pull...