I think that I am getting a slight gas leak through my out post when pouring beer. The beers pours, then a "psst" with foam, then more beer followed by a "psst" with a bit of foam. (Excellent description I know!). I am going to try tightening the out post and see if that makes a difference first. IF this does not work, I figure I can depressurize the keg, remove the "out" ball valve and either try lubricating the o ring on the dip tube, or replace the o-ring entirely. What would be the best practice for doing something like this? I was thinking depressurize, remove post and lube or change out o-ring, then pressurize and purge 2 or three times. Thoughts?