The Drayton SM2 timer for my boiler is not working properly. The water and central heating controls light up and work fine when activated but the mechanical timer part has stopped working. I've removed it from it's back plate and all connections seem fine. I took the back off the unit itself and found the timer part to be quite hot. Is this normal? I've had the timer for just over a year. It doesn't seem all that long for it to develop a fault considering they are quite expensive to replace. I'd be grateful for any advice