Why has my Dimplex storage heater stopped working?

I have a Dimplex XLS12n storage heater which seems to have stopped working and wondered if anyone can help. I used it about this time last year but not again till this week, when it seems to not want to charge/heat up overnight. I've checked the MCB hasn't tripped and is in the ON position, and the wires in the power socket - all seem ok. When I switch the INPUT dial clockwise beyond position 1 it clicks, and then again when positioned back to 1. I removed the heater outer panel:- and checked (reset) the cut out (it's a metal tag type), though I have never put anything on the heater which may have caused it to cut out. I heard a slight click but presume this doesn't click into a different position - just resets by contact? As I am unemployed with no funds at the moment, I wondered if there is something more I could do - or from my descriptions, what might be the likely cause. In addition, I have looked at the consumer (Hager) unit mcbs and can see one (marked storage heater) where the metal clip at bottom rear of the mcb, by the rail which is in an 'up' position, whereas all the rest are in a lower position where you can see a **** or cut out - presumably where one manipulates with a screwdriver. I was hoping to get this mcb out and see if the fuse wire has blown. Note all mcbs are in on position - none have tripped. The storage heater seems to be directly wired from the consumer unit to the supply socket (ie no fuse on the socket supply) just the on/off switch. It seems strange to have just stopped working. I am a competent DIYer with electrics. Thanks.