Gainsborough Shower Problems

I have a gainsborough 10.5Kw Electric shower. It has suddently stopped producing hot water. Worked fine in the morning, came to use it 10-20mins later, water stone cold. I have checked all the power feeds etc, and power is getting to the shower, and after putting it back together, and running for a few mins, I heard a noise like a kettle boiling, and it started to work. Day after, back to cold again. I suspect its the element or something is not working, but has anyone any ideas please, such as filters blocked etc etc, before I go and buy a new one.

BTW, can you get spares for these showers.

Cheers

Chris

I have had another look at this shower, it appears that there is a plunger that closes some contacts when the shower is turned on. This plunger is not moving as much as it should. Anybody any ideas why. When I manually push the plunger down, and try the shower, works OK, but when turned off, the plunger clicks back, and back to square 1.

Sounds like scale build up in the element.
With the price of replacement units I would exchange the whole thing go for one with a scale inhibitor.
Pete