88 80q no start

[Quattro8880 at aol.com]

I recently replaced the head on the NG motor and after getting it running it 
had an idle isolation. A "friend" messed with the co adjustment and now I 
can't get it started. Is there a position for that adjustment screw that I can 
start it in and then adjust to the +- 0 ma ? Does that screw bottom out clockwise 
or counter clockwise ? Could it have come all the way out of were it's 
supposed to go?  What or how can I check these things ?

TIA