Ray, OK. The is the early PS-2 5V board. First, to repair the Lead A does not require changes to your Slave A. If the board is totally bad, the recommended repair is installing a PS-2 3V board with 5V connectors, with a 4 ohm speaker and 2.4V battery with harness. I have done this repair on several early E-6/8s including the ACL.
Now that you have given some more information: If your first problem was loss of all lights, that is a chip on the board. It actually also controls smoke fan which you don't have in your unit. This can be fixed by me.
The direction control may be a different matter, and while some of the components are exposed, if it is the micro controller it may not be repairable.
You could send me the board and I could test and repair, but if motor function can't be restored upgrading to the 3V system is you best alternative. I have the parts to do this and I am a MTH Tech, so it comes with warranty. You can contact me via my profile e-mail. I would only need your Lead A to do this. G