Hi all, I'm chasing what I'm sure is an air leak somewhere in my MS361 (erratic behavior I cannot eliminate via carb adjustments), and I don't have easy access to a compression and/or vac tester, so before I retrieve said tools and tear it down to check the oil seals, piston, rings, etc., I was wondering if the impulse line should swivel/rotate 360 degrees where it attaches to the the crankcase/cylinder? I've never actually replaced an impulse line on these Stihls, but I did notice when I was checking my impulse line (which is solidly attached to the nipple) that I can rotate it like one might the hands on a clock. In other words, the nipple itself rotates in its seat. Is this normal, or might this be a source of air? Thanks.