The single screw lock is a bit questionable in terms of grip; the screw hole is cut superficially in some places (the metal around the hole protrudes inwards). With some slightly lower switches (e.g. Laney pedals or some soft-switches with a round cap) it is necessary to place the cap higher, otherwise it will not turn the pedal on/off. This means installing it higher, which eventually slips lower with pressure without padding and the error is repeated. In this case, I suggest lining it with some kind of cardboard/felt.