Florescent in Marquee not fully lighting (Galaga)

[JenTime]

I have a 1981 Galaga and as I continue to do a once-over of it I have been struggling to get the florescent light (possibly ballast) to fully light the bulb.
I have tried a 15W T8 18" bulb and a 15W T12 18"
Neither fully light.
The T12 gets the closest (picture attached).

Trying to determine what the issue is.
I am trying not to to just replace the ballast with an LED one as I want to keep the cabinet as original as possible.

I saw on one post online that someone was selling "Galaga" 14W bulbs but I do not know if that was a typo or if it really was 14W back then.
I have been unable to find a 14W 18" T12 to try though.
The only 14W ones I have seen online are 15".

Does anyone know if the 14W is a white rabbit I am chasing, or if it really was 14W back then?

One test that works...
When I use the multimeter I get a good voltage and I can giggle the T8 to the point it fully lights, just that is when it is not rotated into the connectors, so it doesn't power on after turning the cabinet off/on.

Any good ways to solve this?
I've also tried making sure the connectors are fully touching, and they seem to be.

[Ken Layton]

Did you also replace the FS-2 starter located on the back of the light fixture?

[JenTime]

I just read up on that  and have not replaced it.
Online it said that it is the culprit if the light doesn't turn on... now whether mine turns on is up to debate as it produces light but not full light of being ON.

So yeah.. I might pop by the store tomorrow and pick one up.

The one that I yanked out before seeing your message is the original one, so it is 40 years old.

[JenTime]

Yes.. it was the Starter.
So it works again!
YAY!!!

[Ken Layton]

The switch contacts inside the old starter were probably stuck closed.

[Zebidee]

Starters are really just electrolytic capacitors (open one up to see the bag of electrolytic fluid) to build up the starting charge and, as we all know too well, they wear out/dry out over time.

Usually a good idea to change the starter whenever you replace the tube.

Modern LED replacements for fluorescent tubes have the starter built-in, use less power and generate less heat. So a good idea all-round.

[JenTime]

Yeah makes sense. Still learning/relearning some if this information.
Glad I didn't buy a replacement ballast before figuring out the Starter is removeable and the people here saying what it does.