I made a quick spacer for the TRFightstick CPS3 volume knob as I had replaced the POT on the CPS3 with a smaller dial and one with a flattened side. It's a super tight fit, but it's meant to be since the knob is friction fit. Maybe you replaced one too and could use this spacer.
https://www.printables.com/model/1800448-cps3-hursuit-trfightstick-volume-knob-spacer
https://www.printables.com/model/1800448-cps3-hursuit-trfightstick-volume-knob-spacer
