I am very fond of older (JM marked) Marlins but have discovered that the JM mark does not guarantee a gun without flaw.
Recently I traded for a model Marlin and while working with it this morning with a newly installed tang sight I noted that the barrel is over clocked about 10 degrees. My fix is to install a band type front sight ramp. This would probably work for some of those over clocked Remlins running around.