Just from memory here, but isn't it "Death dive!"

SOLD SOLD SOLD
Just posted a set of convolux plastic protectors for Fathom. They are green. My wife ended up not liking them. See the add at: https://pinside.com/pinball/market/classifieds/ad/92699

Wow. That’s is really amazing. That is truly a find. Looks to have been serviced by a less then expert repair person, but nothing bad that’s visible. Will need new drop targets. Check for and remove any batteries on the CPU board. But Wow, great find.

On your video, I got the sense that you did not drain both of the balls after the second time the ball was captured. I suspect by draining only one ball, your machine interpreted this as losing one of the two multi-balls putting you back into single ball mode and that’s why the in- lines went back up. When you did it the second time and didn’t drain a ball, it assumed you were again in multi-ball.
Within the single ball mode, when the ball is trapped, the in-line targets pop up. Once released, you are in multi-ball mode and things act differently depending on how many balls are in play. After the final ball drains, (triggering advancing to the next ball in play and collecting the bonus) everything resets back to single ball mode.

However, in multi-ball mode, after the in-line drop targets are dropped and one of the balls end up in the saucer again, the in-line drop targets do not pop up. The ball just sits in the saucer with the in-line targets down. That ball is then only ejected from the saucer when you complete the left playfield drop targets of the matching color (green or blue depending on which saucer your ball currently rests). The fact that your video shows the second ball hitting the star rollover and eliciting the “help me!” quote is consistent with what I’m describing above.
If your ball is in in this state, and then you drain all balls in play and advance to the next ball, the targets should reset. Mine do each time. If I release a trapped ball by knocking down the in-line targets in subsequent balls in play, it acts the same as I’ve described each time. There is no instance where on a new ball in play that the ball is not trapped and the in-line targets go up the first time.
Try your test again, but remember that your machine will think it’s in multi-ball until it sees two balls drain and you collect the bonus. If you want to test the reset within multi-ball mode (with out advancing/collecting bonus) make sure you drain that second ball that was stuck by the trapped ball. It should count down your bonus, reset the targets and advance to the next ball in play (unless you have earned an extra ball, but just avoid that for now while testing your game out)

I am thinking it looks more like a planarian, but that aside - sounds like there must be a joke re the wires not reaching?

I know there is a very nice original for sale that’s at the same price as Shay sells his awesome reproduction BGs.

Look here:

https://pinside.com/pinball/market/classifieds/ad/119332

Nice on the Fathom PF swap. Came out great! My pairing is Fathom and Flash Gordon.

That looks great! Nice job.

Just a thought, but have you looked at the switch matrix on your playfield wiring diagram? Seems like your problems may be related to A4J2-9 on the matrix if I'm understanding what you are saying. If that's the case, look for a little brown wire with yellow striping at each component in the line. It's so easy to miss one since there is most often two wires of the same color [kind of like one in and one out] connected to each switch, it is easy to miss one that has busted loose from the swap. Also check your drop switches to make sure that they are actually connecting. I had to readjust mine and clean them after I did a swap in the same manner as you for my Flash Gordon. Your drops will not reset if a switch is not properly closing or there is a breach in the switch matrix - it does not "know" that all of the drops are down, so it does not reset. Same is true with your ball through switches. That is almost always a switch issue and I note the switch matrix shows "1 left of outhouse" on the same line as the saucer, a middle drop target, and the third inline blue. When I started things up I had similar issues and it was all a little wire off here and a switch out of alignment there. Good luck - it will work out!

Interesting idea. I also need one. I’ve not found one, but only been casually looking about.

That’s a beauty. Hardtop, new PF or original? Looks great no matter which.