Ok, so here's the bad news
The old Tx I planned to change the pots on is a Futaba Challenger FP-T6NL. I attacked the right hand gimbal to extract the elevator pot...
It's VERY small, The *body* of it is 13mm diameter x 4.5mm thick, and the (unthreaded) neck is 6mm diameter x 4.5 long.
The shaft has NO flats and is 3.5mm diameter x 10mm long.
The pot value is 5k linear. No wonder it didn't work too well! The trimpot measured 10k.
I have unearthed one of the *small* Maplin pots, (wrong value, anyway...) and there's no way it's going to fit. Much too big!
I then hunted in my *bits* box, and found 4 x 500k pots with *CTS 7747* on the back. Although these are somewhat smaller than the Maplin pot, they *still* won't go in without major surgery on the gimbal. I think any attempt to fit them would finish up with everything in the bin.
So, if anyone finds a source (in the UK) for 500k or 470k pots of the CORRECT size, please let me/us know! The existing 10k trimpots may just do their original job ok.
RR