Reply to Loose Fader Knobs

Just received the green knob/fader set (vci-100) and had a question about tight fit?

The round knobs themselves fit very snug and seem very secure, however, the fader/slider knobs fit extremely loose and easily come off. Is there a 'fix' or 'trick' to perhaps have these fit tighter? Maybe wrap a few turns of tape? glue? something?

Thank-you

BC