First you need to determine what not reading what.

When the drop targets are hit.. does the game give a score?

If so then switch input on this at the board is probably working Ok.
If not, the there is a fault at where inputs go to board, be it a connector or data fault.

If it does give a score then you have a problem from CPU output to driver.
Once again, could be connector or data fault.

Make sure ALL switches are reading closed when all drops are down... if one is out then CPU will not reset them. Do this at the switch input at the board and the switch itself ( one lead on switch.. other at input  board connector) this will tell you if signal is getting to the board

Also check at coin door test... and see if all solenoids fire during test mode

Thanks Gavin,

Yes, when each card is dropped, the score goes up AND when the last card goes down, the score goes up more as if it knows all three are down but does not reset.
I cannot get the coin door test to work. I have game over mode, manual down switch and depress advance. Nothing happens.

J.D.