Most of these old Brunswick commercial tables have spent 50, or 60 years in a pool room getting their pocket facings hammered by dudes that just try to shoot all shots at break speed. You guys know who I'm talking about. Over time this is catastrophic to the subrail mitre of those pockets, so if Brunswick originally cut those miters to 141 degrees, there is no telling what the mushroomed facings are now. It almost appears the one pocket in the pic is close to 150, and rounded like a snooker pocket. The only way to fix that is make a clean cut on the subrail mitre, and splice in wood, then recut to the proper angle, but...and the big but here, what does the subrail look like in general. My bet is that it's stapled out from years of cloth changes, so therefore it probably needs the entire subrail cut off and replaced, then at that point you can cut the pocket miters to the proper angles.