Well my 13-year-old boiler appears to be destined for that great sauna in the sky. The following bits need replaced:

• fan
• circuit board
• pump
• transformer.

Replacement pumps and a fan that could fit in the relevant place are available but the boiler is so old that spare parts for this model are no longer available. Probably over £600 for a new one.

Bugger. So much for getting the Pismo repaired this month.