Canopy frame was moving around on the rubber seal so had to remove the seal. Measured the gap from the bottom of the frame to the fuse with the seal in place - then removed the seal. Made up wooden blocks (as Peter T did) and thicknessed them to hold the frame in the same position as it was with the rubber seal on.
Also decided (after the suggestion on the forum) to do a rough mark-up of the canopy skin before the canopy was attached. Doing it before attaching the canopy allowed the top and bottom of the frame to be marked on the inside of the skin - giving a rough idea of the finished shape. Will now cut the skin to about 1/2" oversize and progress from there.
Shaped blocks under the frame and swivel blocks to go over
