give the jet good clean out , dont disturb the primer cap if you can help it or swap it with one you know ran well be sure to be sure the hole isnt blocked and the filter screen is tiketyboo . hold it too a light look through the filter screen and clean out the main jethole .
if O ring is leaking relpace it too but you should be able to tell . if it leaked air it will leak fuel too so ........ wont run well as you described
