Like said here, check the optos in the subway at the fridge and make sure the sewer opto in test isn't firing from vibration from the plunge. I would pull those two sets of optos and reflow them also could be a simple cold solder joint. I believe there is only 2 sets of optos in the subway one for the sewer and one for the fridge to stage a ball, if your game is cycling twice its probably is not staging a ball down there. My no fear did that and just would skip it after the second try but it didn't stage the ball.
When I 1st got my JY mine was having issues not awarding the dog shot but once it went in the hole it awarded anything the sewer had lit but my issue was the switch on the playfield at the entrance of the dog house if that switch doesn't register the next thing in line is the sewer opto in the subway then the fridge I believe.

Something might be wrong with the White Brown if the issues are across the matrix check in from the switch before 21 the coin door slam switch and after switch 61 upper 3 bank right switch. Switch 61has a diod on it check and verify that is working correctly.
I would also reseat both the connectors on the mpu J208 and J206

It goes on that Coil if you haven't fixed it yet, here is pic of mine.

20190512_181607 (resized).jpg

Is there a good set of custom apron cards out there for JY?

You need to check the switch at the entrance of the dog house. The switch is to the left of the hole in front of the dog house. If that switch doesn't register the only other switch which I think is an opto not sure is in the trough and you are getting credit for hitting the sewer. I had problems with that also, I got it to work adjusting it but it was still unreliable until I just replaced that switch. I would adjust it first and see how it goes.

Cool read. I own a sample with the magnet core that does nothing. The Comet Skill shot would have been cool since I own a Comet also.