would be grateful for any advice. a trevi therm thermostatic shower i have had for 10 year has started running lukewarm. if i change the shower head round to a different spray it sometimes runs hotter or if i move the head forward. i have taken the head off to make sure nothing is blocked everything seems ok apart from a rubber seal in the neck of the head that looks a little out of shape. i am not sure of the actual model after these years but it looks similar to the a300 currently on sale. the shower is an inset model all pipework and parts are built in the wall. it runs off the combi boiler. thank you
