search for trackball disassembly. There are several links and one has pictures and a step by step. It's not that hard, some just use their fingernail but I would not personally recommend that method. You need to take care and not bend the prongs on the outer ring and make sure that you reassemble exactly as you took it out. You only have to remove the outter retaining rind and the internal retaining clip. Don't lose any parts! good luck!