Thanks Matt,
It seems as though some bubbles originate from the Carb end when at idle but quickly get sucked down again as the throttle opens, I saw this on my OS46FX as well but never had any problems with it. Ive closed the needle valve completely and blown in the pressure line, no leaks, I just go red in the face from trying. Ive opened the needle valve 4 or 5 turns and pinched the line from needle to carb, no leaks, done the same with carb closed and piston turned so no leaks in a really deathly quiet room and can hear no leaks, Ive just got sore cheeks and lips from trying to blow into a fuel line very hard. Short using an air compressor (only because I dont have one) to really pressurise the system Ive tried all the possible ways I can think of to test it. Obviously from my observations air was getting in somewhere. The engine wasnt hot enough for it to be methanol vaporising as I read in another post.

Ill pick up some new tubing on my way to the field tomorrow and replace it all if need be.
Ive also just ordered online a set of fuel dots, when they arrive Im going to change the DuBro quik filler though I dont suspect it, Im going to eliminate ANY possibilities now and for future problems as well. I like the KISS principle, had I know about fuel dots before getting the quik filler Id have used them.