The first thing I would check if the number isn't appearing on the back glass is the 0-9 unit, located in the back of the head. This 0-9 unit has a small one point bell attached to it. The match numbers work off of this 0-9 unit and this unit must be inspected with a close eye and bright light.
Make sure the tiny arrow shaped metal pointers sits and rides perfectly over these brass rivets as you manually step up the solenoid plunger by hand and check that there are are no broken wires on this 0-9 unit too, including any of the tiny jumper wires that are covered with a black thin material insulator on them. Sometimes these tiny jumper wires are broken off.
Also the brass rivets on the 0-9 unit might be worn out to point that the tiny arrow shape pointers that make contact with these brass rivets are not making contact. If so, you can rebuild these worn out brass rivets with a drop of solder on them temporarily unit you might be able to find and buy another better condition 0-9 unit. Over time the solder repair will wear out depending on how much you play your game.
Go here to view a video of standard Gottlieb 0-9 unit at
This video can help you trouble-shoot and repair most issues with a Gottlieb 0-9 unit.
To help out and make things easier with your issues on your Cross Town in the future....it would be great if you can snap a few clear detailed close up pictures of your 0-9 unit so we can view and possibly spot a potential problem and in the future what ever other issues you might want help with..... attaching a video of other problems you might be having. The more information the better.