Tele 4-way switch mod with humbuckers

ICBM

If  .022uF isn't doing much, try .01uF or .0047uF - much smaller than that will likely be too small, although these cost pennies so it's not a problem to buy others in that size range if you want more fine tweaking options.

barnsleyboy

0.01uF works perfectly! Good call on the bass cut option @ICBM, very much appreciated. In fact, this may be making an appearance elsewhere in my collection! I'm feeling some experimentation coming on.