my reprapdiscount lcd had very bad contrast so after a tare down i found a small potentiometer on the back of the lcd....Time to get the drills out
started off with a small pilot hole
Then
Very Very carefully enlarged the hole so it butt up against the track. Then with a razor blade scraped back the pcb mask and fluxed and tinned the track to reinforce it
Then i insulated it with some kapton tape
I reassembled led screen adjusted the potentiometer with a tiny screw driver i had insulated with kapton tape and....BINGO !!