Can a Triton Aquatronic w9500s be fixed if it keeps cutting out?

Hello,

As you can see, I have a rather rubbish Triton shower, which keeps breaking. I have replaced the PRV on it already and I have replaced the shower head and the hose. However, a few days ago, the damn thing started to cut out. By this I mean that the water just stopped flowing. All the lights were on and it started working again after about 30 minutes but it is rather annoying that I can only use it for five minutes at a time. I have heard that it could be something to do with the heat exchanger. Is this something which I can fix myself? If so, can someone show me a diagram? Thanks!