Glowworm boiler - pilot flame keeps on going off

[wacky]

I've an old style Glow-worm boiler - model 65-80. Over the last few days the pilot flame keeps on going off. I relight the flame and sometimes it stays on for a few hours but lately it just lasts a few minutes. Is thermocouple the problem? If I've to replace the thermocouple, is one of those universal thermocouples good enough? And final question: how much should I expect to pay for one of those?

Regards

 

[meldrew's_mate]

Needs a CORGI chap to stay legal, cost of T/C is about £10, cost of labour varies around the country, should take less than 1 hour including post fitting safety checks.