Worcester senior 6 problem with pilot going out

[tsiub]

Hello and thanks for any responses in advance.

I have a Senior 6 B/F gas boiler that is admittedly a little long in the tooth now! However it was hardly used in its first 8 years of life (pied-a-terre flat for an exec who stayed once a month and it was on twice a day for an hour to keep some heat in the place) and I have been its owner now for 10 years.

It has had, over the last few years, a problem with the pilot going out and was power flushed and had the over-heat thermostat replaced and all was well again. The problem started to recur and the over-heat kept kicking out until eventually it apeared to have failed. Initially I was told it wasn't possible to get the exact replacement part and a modern "alternative" was fitted. During the wait for the part and its replacement the over-heat was "linked-out" and the boiler behaved itself perfectly. The alternative part was fitted and it too kept kicking out. I then sourced the right part which has now been fitted but now the pilot goes out after some hours of operation WITHOUT the over-heat having been triggered .... This suggests to me that there is another heat sensitive part failing somewher and wonder if anyone has any idea what this might be?

Again thanks for any suggestions.