if you really are that concerned her we go , switch the boiler off (at he 0/1 switch on the right hand side. get a flat bladed screwdriver and gently (as to not chew the plastic) gently i said on the left hand side of the clock prise it forward, when you have the clock in your hand turn the boiler on again and hey presto no more ticking and you can use the roomstat again as normal. NO NEED TO REMOVE THE CASE.