Later on both my machines were converted to allow that inner glass to be removed from the front of the machine with less inconvenience. By turning those wooden rails backwards (swapped left to right so they fit) and then a slightly less wide inner glass was cut and then held in place by two pins at the bottom edge (the same nickel plated pins as used on the playfield but filed slightly). This allowed the inner glass to be removed by just unscrewing the three bolts holding the centre cast alloy payout plate in place, once this was removed the glass could be lowered until it missed the top of the wooden door frame, then twisted forward slightly from the top and lifted out. Because of the conversion the inner glass sits forward from its original position by about 3.5 mm. So the playfield pins had been pulled out slightly to accomopdate this, which stops coins jamming against the glass and pins. After cleaning and replacing the pins it became obvious that there was practically no wear on the extra 3mm that had been showing, but that the pins had spent almost their whole working life at the original depth, with lots of wear. So it would appear that this conversion was done late in the game when the machines were sloppy and jamming more often than originally.
I chose to put the machine back the way it originally was made. As yet I've had no sign of any coin jams on the playfield after about 600 coins. If the coin acceptor is adjusted and working correctly it should stop any damaged coins from ever making it as far as the playfield, and they should be rejected to the right side cup.