That's pretty cool. So often it turns out to be the ballast that is not working and they can cost quite a bit to replace, depending which one is needed, and that assumes you can even find the right ballast. I had a hood that came with a used hex tank, hadn't ever worked, which I knew.
New in the box this tank would have been at least $75., and it cost me $15, which was more than fair, I thought. Then another ten bucks to fix the hood, and it's a really nice little tank. Worth the effort, and a good learning experience fixing the hood so it would work.
The issue with it was the ballast. It had an odd type of ballast that I could not find a replacement for, so I ended up having to pull the ballast out & rewire the fixture. Luckily, lots of room where the ballast had been to fit in the sockets I used in place of the original tube it cam with.
I put in one double ended socket that allows me to use a pair of spiral flourescent bulbs that are self ballasted, which pretty much turn it into a fairly high light tank that grows almost anything I want to put in it.
It works really, really well now it's been repaired. I used a lot of silicone to seal as much of the socket as possible. Even though they are covered by a lens, I figured better safe than sorry.