All signs point to burned up traces right by the relay on the SDB. Patch with wires. There is no transistor for just the left side. There is one transistor that turns on the relay.

Stern made fatal flaw on the SDB design. They put way to small traces going to the flipper relay. If you have a mis adjusted EOS. Those traces act like a fuse.

The flippers do not use transistors on the driver board. There is one transistor to control the flipper relay and if your right flippers are working then it is fine. Make sure you have 43V on all three flipper coil lugs. That will verify that your power chain is good, the EOS switch is making contact and both coil windings have power.

Yup... Look how big the wires are carrying the current for the flippers.... Look how tiny those traces are... WHAT WHERE THEY THINKING!! and there is 4 flippers on big game.

Take some wire the size you see going to the flippers and repair those burned traces. I would honestly patch all four traces since yours all look stressed.

If you are not practiced soldering to a PCB. Grab a junker board and practice putting wires between two points so you don't mangle your driver board.

Solder from connector pole to the relay pole. Practice first, you can damage the connector pin solder pad somewhat easily.

Desolder the relay and connector pins at least most of the way. Strip some wire an appropriate size. Hook the ends for a physical connection. Solder in place.

16 or 18 gauge would be good.

Use solid so you don't get any stray strands causing trouble

I'm having a similar issue on a Big Game... don't really know my way around these classic Sterns.... where is the flipper relay board located?

Simple simple. Clippers have transistors associated with them on the solenoid driver board. (Top right in the head? One of those transistor is not like the others. Sure it’s the transistor though?

Just one flipper is out... other three are working... according to this thread, it could be traces?

Is the bad flipper coil getting power? Does it flip when you ground it?

If one flipper is out I would check the EOS switches first to make sure they are making good contact and opening / closing when they are supposed to.

Well, I confirmed that the traces are all intact on the board and I just received flipper rebuild kits... so let me get those installed and I'll report back.

When you do that it couldn’t hurt to swap that coil with a known working flipper.

Apparently the previous owner installed a brand new coil. But you make a good point.

Hopefully this is just a case of a bad switch

Don’t install a new coil. Check for 43 volts on the coil lugs. You should solve this before doing a rebuild on the flippers.