Hi,

I suggest multi turn pots. Glue them with double-sided tape near the orange caps and use pcb jumper wire to connect to the resistors (the type of wire used to repair PCB tracks).

The potentiometer in the picture is not soldered to the resistor, but you get the idea...

http://31.media.tumblr.com/ca128cd98d3d84d9ff29d52efc6fc045/tumblr_n6yhjviglj1sepsqdo1_1280.jpg


rgds,
m