At 21:57 06 October 2016, wrote:
The trim in our club's K21 is no longer effective and I suspect it is
probably a simple matter to tighten up a nut somewhere below the
front seat
so there is more friction on the trim lever.

If anyone had a moment to confirm my suspicion and had any
pointers, that
would be appreciated.

Mark

The bolt on which the trim lever pivots is fitted with a knurled nut for
exactly the purpose you require!