Okay - 2 things...

Firstly the quickie - does anyone have a PDF (or similar) of the manual for
the above boiler? I've no manuals or anything, and I'd find it interesting
and useful.

Now the longer problem.

When our boiler was 'serviced' the engineer said that the thing which
connects to the boiler thermostat had siezed. I don't know its name exactly
(I thought it was a thermocouple as that's what it looked like on our old
but similar Baxi boiler which slipped out easily, but I'm wondering now
whether its just a temperature sensor). He said it would need to be drilled
out should anyone need to open the boiler. Without removing it from the
heat exchanger, you can only open the front of the boiler a small way.

I thought I would see whether I could get it out last night - it just pushes
in and pulls out. I tried pulling it in and out a little and at one point I
noticed a 'leakage' of some liquid around the hole it went into (and was
soaked up by the material). Not very much - but it evaporated very quickly.
Also noticed a smell of something like solvents. At this point I stopped
doing anything!

Now this morning I noticed a banging sound from 'outside' which I now
believe to be overspill via the expansion tank. Also my wife said there was
"a strong smell of superglue in the kitchen".

Now - I can't figure out where some solvent smelling thing could come from
in an old boiler - unless the temperature sensor thing was actually a tube
containing a solvent which I split by wiggling it. Result was that the
boiler's thermostat no longer works.

Is this a correct guess at what has gone wrong? Otherwise I cannot figure
out where such solvent could come from (its not gas).

Is this an easy fix (something I can do myself if its just insert new probe
and connect to thermostat in boiler?).

Thanks

D