Do a jumper test on the switch matrix of the MPU. Dont have the manual handy, but it should identify the row and column connectors on the board. Pull the two connectors, and using a small jumper wire, jumper pin 1 of the row to each pin of the column, one at a time on the board connector pins. Do this in switch edge test mode. Follow along and see if every row/column combo corresponds correctly to the matrix. Then move to pin 2 and repeat and so on, until you test all 64 combos.

If they show up correctly, then it's a wiring or diode issue in the playfield. If they dont, then board issue.

For unusual behavior like that probably the data buffer IC took a hit. RD board is fine, but yours could be fixed relatively inexpensively, especially if you have the tools to do it yourself. If you want to sell the board as is, let me know, as I have a maverick also with an RD board, but wouldnt mind pitting an original back in.

Page 78 of the ipdb schematics....would be IC 8J or 8H.