I have a spare Stern knocker assembly that came out of a Meteor if anyone needs it. It may not have a Stern coil but it has a good coil in it. Not an easy part to track down because they burn up and are always missing. $25 shipped.

In THAT case, someone has probably set the replay score(s) to be VERY low... You likely don't notice it because there is no knocker in your game. Knocker fires when a replay is awarded. It's a trick that Bally and Stern owners use to keep credits on a game so you don't have to keep opening the coin door.

Well, in the manual there could be sound settings that were reset to factory defaults when you cleared the memory... They are most often set in the "push button" game settings on the coin door. I would look in there first. Would say something like "background sounds only" or "feature game sounds" in stead of "beep and blips" or some such designation.

If there is nothing in the manual about sound settings, I would bet on a bad set of ribbon cables or corroded pins.

That's the "key" so that you can't plug it in where it does not belong.

There is one in almost every connector of every machine ever made.

Get your meter out and test those two wires to determine which one has DC power. (It's probably the Blk/yellow)

To test this: your black multimeter lead goes on the side metal rail of the game (or ground braid) and the read multimeter lead goes to each wire.

Solder the power wire(s) to the white banded diode lug on the knocker coil.

Solder the other wire(s) to the other non-banded side of the knocker coil.

Pay close attention when you first power it on. If the coil locks on imeediately, you have a bad transistor on your driver board. I mention this because it was very common for the knocker transistor to fail and the knocker was missing from your game for a reason (it probably burned up due to a bad transistor). If not, no worries then.