Look for small cracks around the lockplates, are all the pins (screwheads) in completely, they should slightly protrude from the lockplate. I would also check trigger pulls. It would be great if you could take the lockplates off to check the condition of the lockwork.
Ditto, but add pull the locks off and inspect edges of the lock plates to ensure they are beveled. Square plates can crack the wood. Check hammers for cracks just below the head. Check sear engagement. It is not unusual to find more wear on the right lock. Check plate inletting.
