Dan Gravell wrote:

Hi there,

I have a very small allen key screw which screws into the bottom of my
shower mixer unit to fasten the thermostat and control to the shower.

I recently had some problems with the shower running colder than normal
so following the advice of the manual (and this newsgroup) I took out
the thermostat, flushed it and gave it a good clean, and reinserted it.
Unfortunately this didn't work, and after a phone call to the
manufacturers I got sent a new unit (can't fault the service btw, the
company was Marflow).

Now, the problem is that when I went to install the thermostat, I
realised the screw's inside has become threaded, in that it is almost
circular and not hexagonal any more. The allen key (which I suspect was
probably slightly too small in the first place) just rotates in the
socket. This "threading" happened when I rescrewed after trying the flush.

I tried extracting with all manner of pliers, assuming I could get a
decent grip and twist it out, but to no avail. Perhaps I screwed it in
incorrectly.

Anybody got any suggestions for extracting this screw? I thought
possibly using a junior hacksaw to create a slot to use a normal
screwdriver to screw it out. Would that work? Or would it just mangle
the screw?

Thanks, Dan

p.s. Sorry if threaded is not the proper term... Perhaps someone could
suggest a better one to help other people searching for similar problems.

You have had one good suggestion - glue in the key.

Another one is to invest in a small file, and an over seze allen keye,
and file it down rather tapered til its a very tight fit, and hammer it in.