The first sign would be mushrooming firing pins, gun hard to open because firing pin is "stuck" out far enough causing drag, secondly would be when you take the gun apart...what do the hammers look like are they all dented up, can you see any hairline cracks in the metal(possibly over hardend parts are common too), can you seen metal shavings/spalling on the bottom of the action (metal possibly from the hammers, or even the sear engagement surface area. Thats it for my experience...my only other experience is packaging up the gun and sending it away to have the thing fixed. :-(
