Hi Matt sounds like good news about the seals , you would have definately seen engine oil come out if they had gone!Make sure your float levels are set exactly , this may be causing the intermittant firing , due to flooding ( just another possibility to trouble shoot).With the float bowl off turn the carb upside down & measure form the edge of the carb to the top of the float. It should be 27mm.Also , before you re-fit the bowl connect the carb & check the needle seat for leaks. Keep trouble shooting ! I did & it all panned out in the end ( often the obvious wasn't always what to look for lol) Cheers Paul