We’ve added some muffling to the bells to use when we have a practice (usually Friday evenings). Essentially this is a strip of rubber shaped around each bell’s clapper and fixed using velcro so that it lies between the ball of the clapper and the bell itself when the bell strikes. You can see one in this picture of the tenor – the largest bell at St Peter’s. When we are not practising the rubber strip is simply rotated by a quarter of a turn and the bell will sound normally.
At least that’s the theory. Occasionally we still have some slippage and a rubber strip rotates itself resulting in a bell sounding un-muffled when it shouldn’t. This is despite the non-slip paint on the clappers. When this happens we have to ring the bell down and usually one or more of the other bells as well to make it safe to access the offending clapper. We are still working on why this happens!