Also, you should definitely check the fuses and fuse holders in the bottom of the cab, if you have a multimeter, you can check them with that, visual inspection is not reliable.
One additional step to this tip......pull each fuse and check it out of the cabinet.... I used the multimeter on each fuse at first when I got my Pole Position and they all checked out.. so I did a bunch more stuff for days and still could not get the game to go on... after inspecting the fuses again I found out that one of the fuses was unwelded on the inside and even thou it was making contact with the end cap, the voltage was not all going thru. Actually the glass and inside fuse came right off when I pulled it and realized the problem was the fuse was just too old... so don't test the fuses on the fuse block, if possible replace fuses too. After all the work that we put on replacing worn out parts why not replace the fuses too?