Thank you all again for taking the time to suggest solutions to my problem.
I have reassembled the trigger as it came to me when I got the gun. I’ve uploaded more pictures that better show the trigger components as assembled by me.
It seems to function as a trigger ok but not latch due to insufficient travel of the piston in to the trigger block, sorry if I’m repeating myself in this matter but I can’t see how it would have worked even before I got it.
More pictures.

http://i513.photobucket.com/albums/t...psnixh5cjt.jpg

http://i513.photobucket.com/albums/t...psmcdqprgo.jpg

regards
phil