Transistor ID help on arcade monitor

Hey folks,

I know there’s some technical minded people on here, I’m wondering if I can get some help with an arcade monitor chassis.

I have an old Nanao MC2000-S monitor from a 1982 Pengo cocktail cabinet that doesn’t show the color blue. I sent the chassis away to to a place to get it repaired, they gave it a new cap kit and said it was fine.

But the color blue was still missing:

This was years ago. I figured that meant the blue gun in the tube was toast, so I never tried anything else. For some reason this past weekend, I decided to try to mess with it. I switched the blue and green wires that go from the chassis to the neck board and low and behold:


We’ve got blue showing up in the green spot.

So this means that my blue gun is actually fine and this can be fixed on the chassis, right?

I did some more research and on the monitor and came across a helpful post on KLOV with these diagrams:

As you can see, there’s three transistors on the blue path through the chassis, from the input to the output. So I’m thinking it’s an issue with one or all of them: q105, q106 or q303.

Is this a correct assumption? I’m thinking maybe also it could be that one of the pots is damaged, either on the bias or color amplifier?

If this is the case, then I need help ordering the right type of transistors, the types of which are listed above. I can solder and have a simple multimeter, but I would need some basic guidance on how to install them. And probably the potentiometers, if it comes to that.

I feel like I’ve listed everything, but here’s the manual in case I missed some stuff:
http://www.arcade-museum.com/manuals-monitors/nanao-mc-2000S-sega.pdf

Thanks for the help folks.

Edit: here’s the actual post on KLOV:

He says all the pots are just 5k ohm pots, but the way the monitor controls the colors is reverse the way that most do, the neck board pots control the color strength. And obviously his issue is different than mine, but it’s a good reference.