As you know I have fixed my machine from being technically destroyed to something decent, lately everything was going well the machine served everything, a month ago I started to see that a line of 8 bulbs was starting to fail, I knew quickly which Tip42 it corresponded to quick change it, this did not fix the problem, I had to change the 2n6427when I changed it the line of lights worked normal for a while, then it turned off again, I thought it was the connector that connector is already something old but when testing that everything was fine in a matter of cable and connection (I checked this with a voltmeter) it seemed strange to me that this failed, I thought this happened when you changed old components for new ones, something like that I thought like it had to adapt to the card or I don't know , that problem appeared suddenly the occasion was very random, I thought it would be something that would only be solved, yesterday I took out the main cards that are the MPU and drivers to give them cleaning maintenance verify that everything was correct, no track crossed with another, some bad welding or cracking, and then put them back in place.
At the time of turning on the machine, a line of 8 bulbs began to fail, it is to be specific is the one that goes from the bonus 1000 to the bonus 8000 in my firepower II machine These spotlights began to light up, they continued to perform their display function I knew it was bad that they would light up like this, because they would cause them to blow or a fuse would be blown.
Check if the transformer was good, indeed it is, what I think may be is that the PIA circuit of lamps is already failing, because the line of bulbs that are failing I had previously put a new Tip42, a new resistor and even a new transistor, if I can't find the 2n6427 I put a 2n3904,I do not know if that is why they have failed, although that transistor had been working for a week and lit everything very well, so I do not know what it can be, does anyone know how to help? I find it strange that the connectors are correct but that certain lines of lights are suddenly disconnected, so what solution is there?

This is what seems strange to me, which causes some lines of eight lights to disconnect and connect randomly in the machine, if it is not a connector or bad contact

I just solved the problem, if it was the transistor but I don't see why not change the PIA, do you know what number it is?I also saw that the connector if it is failing the same, will you also know where can I get it?