O rings fitted from local car shop 20p for 6 only need 2 not ridden it but running on the stand the tick over seems rock solid at about 1100 rpm hope to get out on it over the weekend.
Incidentally both mixture screws are about 3/4 of a turn out from lightly seated,
if your tick over and starting are a bit erratic it's worth the cost of 2 o'rings just to rule them out.