I've had an issue with my Flash Gordon that I attributed to a power surge, but it was probably just a coincidence.
I've now determined that something located on the playfield makes the F5 fuse blow (cause it's fine when I remove the J1 plug), which controls the GI and apparently part of the sound (sometimes just the speech will stop, sometimes all the sounds).

I just can't seem to find the source of the issue, as I can't see anything that could cause a short-circuit on any of the lamp sockets. Sometimes it'll work again for a couple hours of play after I twiddle a bit here and there under the playfield, but the fuse will blows again at some point while playing.
I know I'll have to be a bit more systematic to locate the cause of the issue (I would appreciate some advices to get there the most efficiently possible), but I might go through a lot of fuses.

To get to the point, F5 is a 20 amp fast-blow fuse, and I've had no luck getting a 16 amp circuit breaker to work in its place. I'm afraid to use a 20 amp breaker because I believe it'll be too slow compared to a fast-blow fuse and it might damage the circuit.
As far as I can tell, there's no circuit breaker with a value between 16 and 20 amps. Would it even be advisable to use one ? Am I condemned to just use lots of fuses ?

How do I recognise Pin 1 ? I searched the manual and the web, but found no answer.

I should add that with the problem fixing itself, for a time, when I mess with the underside of the playfield will make the identification of the source of the issue quite a challenge ...

Oh wow, I really can't read apparently ...

Anything standard in the electrical realm really is rocket science to me, unfortunately.

So the lesser the load, the smaller the amp value of the fuse is needed ? Because, apart from the blinking lights (which are controlled by another circuit and go through another fuse), I didn't put any bulbs behind the backglass. It should lessen the load, and yet my 16 amp circuit breaker doesn't seem to be able to take it.

You'll also have to explain to me how you set up the jumper wire to go around the disconnected area.

Lastly, I'd like to know if just removing bulbs, as it is implied in the "Repairing Bally, Stern Pinball Games 1977-1985" doc, could help pinpoint the source of the issue. It's just way easier than desoldering and resoldering wires to sockets, especially with the playfield in its vertical service position (what a pain it is to work under the playfield of pinballs of this era).

As with my previous pinball, a part of my clean-up routine consists in removing every bulb, testing them, cleaning them and tossing away any suspect or loose one. So no issue in that department.

Buy an air compressor. Check. I've been meaning to buy one anyways to dust of my legos.

Oh man, one of those too ?

Yeah, I've already read your guide, and even though it would make things easier, I'm just not going to put one in my apartment. Two pinballs is the most I can do in a space that I share with a wife and a baby.

Now that you mention it, I suspect that something I've done could be the culprit. I have two or three sockets that are visibly new (they were there when I bought the machine), but none of their bulb are working. I didn't know what to think of it, and I tried to put some solder on the tip of one of the sockets to see if it would fix it. Don't look at me like that, I read that somewhere ...
Anyways, it was sloppy (what could I expect with the playfield in a vertical position) and it failed miserably but didn't seem to cause any short-circuit. I don't know ...