Electric Shower won't switch on?

I've just installed a Triton electric shower. Everything seemed to go well until I tried to turn it on and nothing happens.

The breaker is fine, and the light on the pull cord is lit up as normal. The power light on the shower itself seems very faint. I found a similar question on this site which suggested that a worn out pull cord switch may be cause of the problem, does this seem likely in my case too?

Any input would be greatly appreciated.