Hi,

I have an old Potterton Netaheat boiler, which was working fine until recently. Now it doesn't spark all the time. Even if the gap between the electrode and metal grate is very small, it won't spark consistently. If the gap is too small, it won't light the pilot light. Do you know if this is a 1) eletrode/HT cable problem, 2) Spark generator problem or what else it may be. The unit is earthed well.

Also, so that I can order new parts, how do I find out if it's a Mk1 or Mk2 unit? Any identifying things to look out for?

Thanks,
Steve