Dont be daft mate, just message me your addy ill send em over. I got a bag of fifty for less than a tenner, and as far as im aware they are up to the job (recommended by goodguy guru mike). Even if it doesn't fix it, its another thing out of the equation and problem. if you need o ring silicone grease (youll need it to get the buggers back in without damaging them)ill send a bit of that too.
No I dont think the float heights would alter from how you set them. Its gotta be carb related I would have thought.