I have an issue with my electric shower. It intermittently fails to turn on when I turn the dial on the shower. The power indicator is on and when it does kick in it provides hot water and works as expected. When the issue first presented it could be resolved quite easily by closing the valve on the pipe that feeds the shower and waiting for it to start whirring. Unfortunately this seemed to take longer and longer to work and over the last two mornings has failed to work entirely. This morning I got frustrated and used a little percussive maintenance and it kicked in with no issue again. For a number of reasons I currently cannot afford a new shower and wanted to know what the potential causes of this might be so I can address them in order of cost. The fix with the valve suggested to me it was an issue with the water pressure but this morning seems to indicate that some part within the shower is faulty. Could you advise?