4148 were used by other manufacturer's at the time to replace 1n4004 on the switch matrix, but Gottlieb is fussy and wants the 1n270's for some reason. While it may seemingly work, the 270's should be used instead.

Just repeating long ago wisdom from RGP and other places. Never tried it myself.

All system 1 games' displays blink when switches are hit, normal. What it decides to do with them later, that's a different story.

I had replaced a Sinbad's spinner with a Black Hole one for better spin response and it was the same thing, 5-6 registrations. I think it's just crappy. That was my only game with an original system 1 board and it's been moved out a long time ago, so I can't even try the pascal replacement in it (my other system 1 games do not have spinners..... countdown even with the pascal board misses a drop target sometimes if you get a LOT of them down in a very quick interval, kind of frustrating when that happens.)