So, first time poster, but love the place thus far.

Space Invaders:
Interesting problem of which I am trying to understand what is going on...
I had just installed a new Alltek MPU and Solenoid Board, seemed to be fine, then I noticed that sometimes (maybe every 5 flips) the flipper activation will trigger the passive bumper (not pop bumper) sound and will register the 50 points on the screen. Now the 4 top passive bumpers (not pop bumpers) wont register or play sound when they are hit.

Stranger yet sometimes (seemingly random) after a round when its adding the bonus it will take several seconds to add everything up. Its long enough that the sound effect sequence runs its length and there is silence until its finished counting up and the next ball is cycled.

Other than the two boards getting replaced the rest of the work has been just play field aesthetics and changing the bulbs to 47s. I also had to replace female connector 8 on the rectifier board since it burnt out (used the unused female from the #7 key right next to it).

I am still pretty new at this so any help is a great help!

Thanks in advance

Does it makes a difference that these are the passive 50pt bumpers at the top (just for scoring, no kicking spoon) not the pop bumpers below them (which work fine)?

I still am trying to understand how those problems could, or maybe even arent, related to the randomly happening slow bonus score adding after a drain that appeared at the exact same time.

You were right. I had done this prior and checked my switches too.... Well, double checking found that the bottom left slingshot switch was in contact. That was disabling the entire top-field passive bumpers and scoring! Once I adjusted it everything came back online and the random scoring/sfx stopped.

Man are these things fun to learn on!

Thanks again everyone.