[quote name='pfretrock' timestamp='1428576077' post='2742525']
My mex p has a solid brass pot shaft and solid metal knob.. Have they gone cheap?
[/quote]Not 'gone cheap' if they are CTS pots, solid or splined shafts are the same price but require different knobs to suit. The OP doesn't say what shafts his has. Other pots are available of course
The split shaft splined type are not designed for knobs with a grub screw fitting, they are generally a internal splined knob with a push on fit.