"Is the pin oxidized enough to cause this?"
Yep...your machine is what....30+ years old? lol
I can clearly see in your photo above that the second pin from the right on the white Molex power connecter is browned and burned out.
On top of it is the 2nd green ground wire.

Have you checked the three fuses on the power supply yet?
Top fuse = 8 amps
Middle fuse = 6 amps
Bottom fuse = 8 amps.
These should all be quick- blow glass fuses with the thin filament inside.
Check all three fuses with a multimeter.

okay...if the fuses are okay.
There IS something that you can try.
With the door opened and the power switch ON, slowly wiggle the Molex connector upwards on the male motherboard pins.
As you are doing that, observe closely the reels.
If you get power to the reels, they will jiggle slightly like as if they're being energized.
That's when you stop moving the white Molex plug.
What you were trying to do is get a fresh. cleaner electrical contact between the male motherboard header pins and the Molex females pins.
Feel the resistance of the reel basket by moving the reel baskets with your fingers... move one reel basket a few symbols off, up or down, after a few seconds, the reels should spin back to wherever they were before you moved it.

Also... the display should be showing something on the reel glass display....at least the last rightmost one that says [Coins Played].
Don't worry about the 25 cent denomination light - it's probably burned out?

What I just told you here is sort of what kind of behavior you should expect from your machine as you fiddle around with it testing stuff.

Oh...below I've attached your photo, but I outlined a 6-pin black connector that should be plugged into the [J13] header socket on the motherboard.
It is located right next to long 20-pin [J10] header socket.

Click on photo below to enlarge if you wish...>>>

I saw some of these at a thrift store last year and I didn't buy them. I kept thinking about it so I went back but they were gone.

If I'm correct, Sigma uses a Translite in between two thin layers of glass. If you soak the glass in a mild soapy water all 3 pieces will slip apart. You just need to get some clear glass that size. If they used the same method on that machine you might be lucky and just the front or back section of glass is cracked.

Chris

Service button doesn’t do anything. I’ll change it back to system and see what happens.

I changed 7.2.1.1 Validation type from System to Standard mode and the printer works but still no TITO.

I checked the cable and ribbon cable and everything is good. I now have the light blinking fast which is telling me its communicating. I went through the set up again and it will not give me the option on 3.4.1.1.4 to disable anything. I can only choose between single and multi reporting. The printer is still saying " sorry, printer unavailable" and it still will not accept tickets that I printed before i got the TITO.