"Andrew L" com wrote in
message ...

snipped but trickles
out the end, back along the bottom and is absorbed by the wall. The
plaster on that wall is blown. :-(

Can I suggest as a temporary measure until the problem is cured, that you
tie a little bit of thin string or strong cotton around the outlet of your
overflow pipe so that the trickle is drawn down the string and clear of your
wall.
Regards
Tom