No battery corrosion at all.

The LED may flicker at first, then go out or it will flicker, then come back on and stay solid.

No, it doesn't

No I haven't been back to the machine yet. I resoldered all of the connectors pins and all of the joints at U10 and U11.

Back at it again. Wednesday evening (two nights ago), I swapped all of the header pin on the MPU and plugged it back in. I had 90 percent of the feature lamps back. Last night, I swapped all of the header pins on the lamp driver. I lost all of the feature lights again. I noticed that if I moved connector J4 on the lamp board, that most of the lights would come back on. I changed all of the crimp connectors on that plug and lost all of the lights again. None of the wires are loose in the connector. Moving that plug makes no difference anymore. I'm going to study the schematic and start checking for continuity through each circuit. I noticed that the schematic for the lamp board is wrong. According to the schematic, pins J4-11 and J4-12 should both be ground but on the driver board, pins J4-10 and J4-11 are ground. J4-12 isn't ground. Are any of you familiar with this? Is there an updated schematic around?

I did get all four score displays working so, I guess that's a step forward.

It's LDA-100 Rev C I believe. Pins 10 and 11 are connected to each other and also to pins 1 and 2. Pin 12 runs to a resistor but I didn't pay enough attention to it to see which one and I'm not at the machine at the moment. There isn't even a wire going to pins 10 or 12, so I don't think it's an issue. I noticed that I wrote "J1" on my last post. I meant connector J4. It has been corrected.

What do you mean when you say pin 8 is the "key". What does key mean in this instance?

That makes sense. Thanks

So I was just flat out wrong about pins 10 and 11 being connected. It is pins 11 and 12 that are connected.

As it sits right now, I have a handful of bulbs that work correctly, another handful that light but don't flash, and a third handful that don't light at all but will if I ground the individual sockets under the playfield.

After looking at the schematic for a while, I noticed that a lot of the lights that aren't lit have somewhat common points on the board. The light for the letter 'Q' at the top of the playfield goes to pin 19 on the MC14514B decoder IC labeled U4. The light for the letter 'U' goes to pin 19 on U3. 'I' goes to pin 19 on U2 and 'C' goes to pin 19 on U1. They are all unlit all of the time. It's the same with the 5 divider lights just below the letters Q U I C, they are all dead too. 4 of the five go to pin 17 on the same four ICs. The 5th lamp goes to pin 18 on U4. pin 18 on U3 and U2 aren't used but pin 18 on U1 is the extra ball light, which is dead too.

So that's all lamps at pins 17, 18, and 19 coming from all four of the decoder ICs that are all dead. BUT, the lights coming from pin 20 will work intermittently, so I don’t know what to make of it.

The credits are no longer showing on the credit/ball in play display as well.

I've gone ahead and ordered new Alltek boards to replace the MPU and lamp driver. Hopefully this will get the machine up and running.

I don't have a logic probe. I do have a small board that works with a laptop to act like a scope but I've never used it.

I'll let you know this afternoon. Thanks Quench

Three of the four address lines showed roughly 1.25V at both sides of the resistors. The fourth showed 5.3V on one side and 0.500 at the other. I believe it was R79 on the lamp board but I don't have it in front of me at the time.

Yes, J2 and J3 being unplugged made no difference. Two nights ago, all feature lights were out. Last night I got home and half of them were working again. The longer I let it sit, the more lights would come on. I'm going to reflow every solder joint on the board.

I hit the credit button at one point to play a game and the pop bumpers started firing on their own, then the machine reset to three flashes and wouldn't do anything else. I pulled the new PIA chip from Action Pinball out and replaced it with the old chip. The machine is working again. I got less than a week out of the new chip. Not sure what happened, but the old chips seem to be able to handle whatever the new chip didn't like. I'm really looking forward to getting the new Alltek boards installed.

I haven't followed up. The new Alltek boards are in and this thing is working AWESOME! I love this game. When I bought the Alltek boards, I told my wife that I would be likely sell it. She played it this weekend and told me not to sell it and that I should move it into the house. I wrung up 3,958,620 points on it last night.

Thanks for your help @quench. I will build a test rig and get to the bottom of the issues on the old board.

This game is so much fun to play. I rolled the score over 9,999,990 yesterday. It didn't recognize that the new high score is 10,015,180. It thought I only scored 15,180. I dig this part the most.