Harry Bloomfield wrote:
It' a mixer, left for hot, right for cold, lift for on, down for off,
with a rotating spout to direct the flow. The handle is becoming a
little loose, there is a bit of free up and down motion befoe it acts,
but I cannot see any obvious fixing mechanism for the handle to the
rest of the tap - other than the blob of plastic coloured red and
blue. The 'blob' is on the handle part, directly under the handle.
Before I struggle to get the 'blob' out, is the handle fixing behind
that please?

Grub screw somewhere. They are not easy to see.