I found this...
This Storage heater spares diagram shows how the heater works inside and what parts can fail, where they fail...
On this site...
http://www.storageheaters.com/spare-parts.htm
To make your own repair you will need some basic tools - a test meter and quite a bit of confidence...
It also says this...
Typically a storage heater has a life of 10 -15 years and these components should last 6-8 years!
Good Luck..., November 2016