Maybe take the head off, grab the shaft with pliers so you don`t twist the knob off. Hold the pad.

What point is it stuck at? Rogers mufflers have a few threads cross threaded on the end of the adjustment rod. So parts will not walk off and fall into the drum. If the muffler is adjusted to this point it can seem stuck. Unless it's corrosion. Then some PB blaster on a Q tip and wipe on the affected area. Let sit and while and try to move. Repeat as needed. Heated candle wax is also a good trick if you can get it to wick into the stuck area. A picture might help too.

thanks very much guys. I didnt know about the cross threading. But my guess is that its a corrosion problem. Lots of humidity where I live.

Carbcity

A can of WD40, a pliers and some cus words should sort it out.

PB Blaster or WD-40 will probably work if it's corrosion. If you don't have luck with that, remove the top(or both) head. Get a grill lighter and heat it up. Use a rag to grip the handle often working it loose. Focus the heat near or on the spot it is seized(I'm guessing the threaded shaft). This, of course would be my last resort effort. Would hate to cut it off.