Investigation of a damp patch on my bathroom ceiling revealed a leak from the shower pump in the loft above. It only happens when the shower is turned on. I hadn't used it for some time as I had a new knee and needed a soak in a hot bath every morning and prefer bathing anyway. Does lack of use cause leaks in seals or whatever? Can it be repaired or will it mean a new pump? I presume I will have to call in a plumber either way. Any idea what it should cost?