Recent instal. This morning wife reported only a dribble. Took a look (at
shower) and found that turning it to cold got us a flow (of cold) but
turning it to hot reduced the flow of cold and we got no hot. Suspected a
blockage but there wasn't one.

Any ideas?

Eventually removed the bar - took control valve off end/ Thought some sort
of spool might be sticking so I gave it a good whack onto a bench.

It is now working. - But will it tomorrow??