checked everything from the air scoop down to the carb- no obvious problems
Checked inlet manifold- no problems
checked over existing carb- no blockages; no float catching; all jets clear; slide OK
changed and adjusted choke mechanism- no difference
would only start when warm/hot with bellows off.......................
Rebuilt another SH20 carb with replacement everything and hey presto- it seems OK
However, any hint of the throttle being opened whilst its being kicked over and it refuses to fire, so I can live with that. It must be sooooo precise/ feckin awkward..............
Both my other 2 Lammies need a tickle on the throttle to start- this one doesn't
I'm off to lie down in a darkened room- thanks to all that offered help support and razor blades
Chris