On Thursday, August 13, 2015 at 9:39:20 AM UTC-4, JJ Sinclair wrote:
Mineral deposits in the valve seal may be causing the leak, you might try soaking the valve in Lime-a-Way or SLR, then flush out under pressure. Try to figure out a way to lube the seat when valve is inside the wing.
JJ

Yup. I would do everything possible to make sure the ball is able to seat correctly including cleaning as suggested, lubricating the O-Ring with glycerin first followed by wax to help it seat. I helped on two LS6 valve-jobs, and they were solved by the above. The mechanism itself is fairly simple, so the likely culprit is seating of the ball valve.

Erik Mann (P3)