I just did a refurbishment of a Black Hole myself, although I started with a machine that was it relatively good shape. It had just been unmaintained and abused by grandkids (and myself when I was younger) in my parents' basement for a couple of decades. I managed to repair a couple of problems with the all-original boards but replaced the original power supply (5v leg died halfway through restoration) with the Rottendog GPS081. I also performed the ground mods, as is required by federal law.

But I had the exact problems with the pop bumpers -- one pops, they all pop. And then they stick down. I took them apart, cleaned everything, reassembled. Replaced a coil here, swapped a plunger there. Wrapped plungers, mounting brackets, and coil stop brackets in cloth and smashed them against things (in attempt to demagnetize). No change. I was really feeling stumped for a while. I ended up ordering complete rebuild kits from Steve, but in the end, I realized this was probably not necessary.

Domino pops: Yes, it's good to have the gap set well, but it's important to first make sure the skirt pin sits perfectly centered in the spoon when at rest. Also make sure the spoon is clean and smooth. Loosen the spoon switch screws and twist the switch body a few degrees left or right if necessary to get it just right. This gives you more leeway to set a wider gap without losing pop sensitivity.

Sticky rings: I'm about 90% sure the problem was not magnification, (I think this is a Pinside myth), but simply weak return springs. The brand new springs I got with the rebuild kit were noticeably stiffer than the tired and weak (1981 original) ones I took out. Once I finished the rebuilds, set the spoon and switch gaps... both problems disappeared and the machine plays great.

Great reading your restoration story! I'm curious if you hit any other snags.

Paul
IMG_0249 (2) (resized).jpg

Interesting... I definitely saw no such damage or strike marks on the yokes or the brackets. Apart from a bit of dirt and wear where the spring rests, the parts were in excellent shape. And likewise -- I could not detect any magnetic properties. (Wouldn't the violent action of simply being part of a pop bumper mechanism protect against polarization?? I'm not a scientist but that seems unlikely in such an environment )

If the yoke is striking the bracket, doesn't that mean the coil stop -- (built in to the mounting bracket) -- is probably badly worn? It seems like the plunger is throwing way too far. I'm afraid chiseling the yoke could allow the ring to start actually hitting the skirt or doing other damage.

https://www.marcospecialties.com/pinball-parts/A-17906

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Hey can you expound on this part a little? My upkicker seems to be a bit too strong. When the gate is closed, the ball flows nicely (not nicely) to the drain, but when the gate is open, the ball hits it so hard it ricochets off the gate up and into the glass, making an ear-piercing and distracting CRACK.

Here's a slo-mo: https://photos.app.goo.gl/yd954vGj145iFRWU9

Were you able to add an EOS? Did it help?

Thanks!

Paul