There was someone who stated cleaning & applying a dab of silicone to the Amal mixture screw here a while back. You know, when the o-ring doesn't hold it in place & the carb always seems to be out of adjustment causing an ongoing headache & general PITA fouling plugs, etc. I just wish to applaud the simple genius of his suggestion seeing as the last rebuild kit I purchased came with what appears to be slightly undersized o-rings. A man can check and set at 1.5 turns out and find it at 3/4 only so many times before the light shines upon him, and I now see the light. Thank you for your mention of silicone. Also to others whom I may not have seen.