Anyone know how to troubleshoot MH ballast? Calgary

[Reef_Geek]

Is this the one that you bought from me?

I did not have any issues with it running from June to Sept before I upgraded. But there is a knob on the ballast that says fuse. I've never opened this but presume you could unscrew it and inspect. Hopefully the fuse just burned out and you can see the filament is not intact (like an incandescent light bulb).

Hope this helps.