Hoover Optima Dial won't select correct programme?

The selection dial on my washing machine will not select the correct programme. I can click it to the correct position, and the various programmes will flash and then change to a different programme. I have had this fixed once before, when it was still under warranty, and I believe it is "simply" a question of removing the dial, cleaning it, and replacing it. Problem is, I don't know how to remove it. Is it as simple as this, and if so, how do I get the dial out to clean it up?