[Arran]

Yes, if you can get some sort of penetrating oil onto the control shafts behind the knobs that would help, but let it sit for a few hours after you do.
If the chassis is leaning backwards tilt the console forward a bit when you spray it in there, maybe put some books under the backs of the feet.
Wrapping a rag or a string around the back of the knobs helps with leverage, sometimes you can keep winding it around until the pressure pulls the knobs off.
Regards
Arran