Hi Wendy I had similer problem with my shower, First turn the electric off at the main, Take the cover off the pull switch and check the wires, Take the cover off the shower box and look for loose or damaged wires, if nothing is visible take the circuit board off and take it to an electrician to be checked it may be a dry joint, DO NOT FORGET TO TURN THE ELECTRIC OFF FIRST, HOPE THIS HELPS
Eric, August 2004