So....has the display EVER worked properly since you've owned the game?
Garbled text on one glass is usually a failed 10939 decoder on the display. These are tough to get as they are long obsolete.

If the interface between the MPU board and the display is not absolutely 100% working, then the displays will be blank. A single bit of information not making it from the MPU to the display will cause this.

With power OFF, reseat both ends of the wire harness.
If that doesn't work, closely examine the connectors.
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Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

I wouldn't replace anything on the MPU yet. I have access to several games/displays so I'd mix and match to isolate. There are other System 80 guys in your area. Perhaps one can help. You can look up Jim Palson at JT Amusements. He's up in Duncannon.
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Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

I can tell you that removing those ICs is tough to do without the right tools. I'd seek out Mr Palson. I know he has the ability and the parts.
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Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info

Good to hear. Please let us know what fixes it.
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Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info

Nice.
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Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info