[JAD]

Thanks Gasser.
Am I correct in assuming that the tickover is totally reliant on the pilot jet /screw combination and that all the plastic idle screw does is lift the slide up a bit? My plastic idle screw has to be barely touching the slide to get a nice "sewing machine" (slow) idle and if I turn it in any further I get a hanging idle which drops down after a few seconds.

Essentially the plastic screw is redundant as far as idle is concerned.