whats wrong with the mpu in the pic you posted?

I don't see any hacks in the photo. The DIP plug mess at TC1 is normal for these later System 80s.
That connector used to go to a 'watchdog' board which would reset the CPU if certain signals went inactive.
Not sure if the Swemmer board added a watchdog timer or not. If so, this mess can be mostly disposed of. One other issue is that 3K pullup resistor from Vcc to the read/write line (pin 7 to 11) is important. Some CPUs don't work reliably without it.

You can just bypass that reset board stuff on the swemmer. It is not needed with the new swemmer mpu. I just got one in my devils dare.

Based on the photo's I have seen - it is a direct copy of the original and did not include an embedded watchdog circuit.
If it is a copy of the original board, why would the reset board not be needed on the swemmer as well?

I would imagine t
You would set dip switches to how ever you had your game set up. Not sure on the locked coil or flasher, were they locked on before?

Mike, I would almost bet that your power supply is bad. They SUCK, and I would just replace it.

At this stage, your old CPU board can still be saved if you remove that Varta backup battery asap. Notice also the burnt 3V zenerdiode in the undervoltage protection which is a design error.....

Removing a battery won't cost you a $ assuming you own a solder iron. If you leave it there for some time you can throw it away for sure. If you remove it might be usefull as a spare or sell it for some $. Just a thought. It is your board of course.

dip switches are just like factory settings

You are telling us the knocker and flashers are locked on. Is the game coming to attract mode, i.e. displays coming up, controlled illumination is running?

Bad Girls is one of the fewer games which are running a 2732 in PROM2 socket. Is the Swemmer board configured like that? Most of the games are running a 2716 in PROM2 socket.

Your old board was affected by a leaking battery.....the 4 pin power connector at the cpu might be damaged and if so, it has to be repinned. Same counts for the switchmatrix J6 connector.

The 5V power supplies are usually fine. Just tighten the screws for the LM338 regulator, replace and adjust the 500 Ohm pot for a sealed multiturn and reflow the header pins and it should last for years again.

If the so called "ground updates" are executed: DO NOT use the heatsink form the 5V power supply as a Ground Plane as it is barely isolated from the +5V (which is present at the case of the LM338 regulator).

Your CPU is not booting. The light strip is controlled by an independent aux lampdriverboard. This means there is +5V. But it is a good idea to measure if the +5V is landing at the CPU board by measuring it over the 100uF cap and eventually adjust it if it is low.

Check the setting for game PROM2. By default it is probably set for a 2716 Eprom. For Bad Girls it needs to be set for using a 2732 Eprom. Ask Fred Swemmer how to jumper it like that or check for info on the silkscreen at the board, I never used these replacement boards.