I would invest the time to drop the exhaust. It will be very difficult if you cannot see what you are doing when you have to replace the O ring and get things back together.
I am sure that this leaking O ring has nothing to do with the flaring problem you speak of. Most likely you have a problem in the valve body.
I got too many cars!! Insurance eats me alive. Dave
78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k