Welcome to the fun of pinball ownership. When they work right they are a lot of fun, when they do not wook they can be downruight maddening.
First off, has this game always done this or did it just start behaving this way? What has been done to this machine lately?
Second, I need to direct you to the great pinball repair guides that are at:
http://www.pinrepair.com/
There is a link to ones that are for Data East, I suggest that you read the whole thing, and there is a special section:
http://www.pinrepair.com/de/index3.htm#switch
on the switch matrix, which seems to be what you are having an issue with.
Finally, you need a manual for the game, It will include schematics, assemble drawings and part numbers. An electronic copy can be found at ipdb.org.
If you look in the manual on page 26, there is a chart listing where the switches are located in the matrix. The issue that you are seeing is related to column 6 since the switches that you mentioned are in that row. It sounds like the CPU thinks that all of the switches in that row are closed when the pop-bumper switch is closed. Read up on the procedures in the above link, and then look for any obvious issues, broken wires, shorted contacts, if you worked on the game, or stuck your arm into the coin-door, the diodes on the trough can get shorted to the metal trough and cause these weird actions also.
Let us know what happens.
Goose