Bill laid this down on his screen :

When you push the gutter into the corner piece, it is loose. Is this right? I
thought it should clip together. Have we missed something obvious?

Alternatively, it looks to me that, if some of the rubber seal could be stuck
to the outside of the gutter, it would make a tight fit. Is self adhesive
rubber seal of this type sold?

You position the gutter over the corner piece, hook it under a clip at
one side molded into the corner piece, then snap it into the opposite
clip. The black line on the white item, is the rubber seal - no other
seal is needed.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk