Ok so you should only ever have 6v on these lamps. This is shown as tappings 8 & 10 on the transformer. From what you describe when the game over relay is activated it blows the globe. Maybe when this is activated it is putting a higher voltage thru these lamps.
With the playfield lifted and the game in playing mode, push the game over relay in and see if the fault occurs. Be CAREFULL not to touch anything dont want you getting a shock.
