The preceding posts have this covered, but don’t forget the Jones plug. With age the contacts can become weak and/or oxidised.

And it will be "C" on the lock RE.

Ohh.... and welcome to Pinside where you will find tech support 24/7 from around the world......

This is new information. if the machine tilts the PF light don't go out on this machine. I'll need to look at the schematic some what.

Do the Back Board lights stay on when the PF lights go off?

Does the tilt light come on when the PF lights go out?

The Lock RE coil is on all the time the game is on, lights on ETC, so it does get hotter than other coils. It will be working or not working, from your comments, sounds like - working.

The fuse you are blowing is on the 24v circuit. When this fuse blows the game will shut down. Even though it can be related to your PF GI ( Play Field General illumination) not working, I think you have two issues.
As for the PF GI’s, check for broken wires and check the Jones plug, (Blue wire).

As for your coil fuse, since it blows every so often, see if you can see what the ball hits when the fuse blows. Look around for broken wires or modifications, new looking solder, ETC….

Can you also use the "PF GI Tester", take a better pic showing us how you have it set up.

The lamp you are testing in the picture appears to be a feature lamp (via the spinner unit) and not GI. To make the Test lamp come on, it must be connected to common side of the transformer (Yellow wire) in that picture, correct me if I’m wrong.

So let’s work on the GI first. For the GI lamps to work we need a circuit starting from the common tap on the transformer. Electrons leave the transformer via the Yellow wire to the Jones Plug then through the GI Lamps than via Blue wire back through the Jones to the 15 amp fuse. From the fuse travel along the Blue/Yellow/White Wire to switch “C” on the Lock Relay (See post #3). From here, if the Lock RE is energised, via Green/Yellow/White wire back to the transformer. And that’s it.

So to make the GI lights working, there is one switch, one fuse, two Jones plug connections, wire and bulbs.

GI Lamps, looks like the lamps under to orange spinner part are GI and normally found under plastics too.

To what have you connected the lamp end of the tester too?

If you think about this, it may help you find the fault. effectively you are taking the fault out of the circuit with your tester.

And don't concern yourself about terminology, we all were NEW to this once..... We like Newbe's asking question here at "Pinside EM Technical help department".

Yahoooo!!!!!!

Once you have solved a problem like this, we should mark this issue as solved. To do that there is a tickbox above the 1st post to the right.