Mine would go up and left but not right or down. Take the switch out, go someplace clean, IE indoors, preferably on a surface you'll find something it it all springs apart. Theres four little 'tabs' that clip the pcb on. Gently seperate these and pull the back off. Inside you'll find a rubber membrane, check the pads on the middle of each 'nipple' are still black and evenly covered. Give them a quick wipe off with something clean like a sheet of A4, theyt will leave a black mark so only a quick wipe to get surface grime off. If you scrub them you'll remove the carbon and render it useless.
Wash the contacts on the board with Isopropyl alcohol, surgical spirit or possibly D4x4 cider if you are really desperate ;) Make sure all is try and reassemble.
The clips do break quite easy, nine has a ring of silicone sealnt holding it together for this reason :)
I MIGHT even have a spare in the garage.
