Need help fixing a Jacob’s ladder

I pulled down the prop from the attic this afternoon. It’s been out of their own use for probably over twenty years. I cleaned off surface rust from the wires and fired it up. It worked, and then it didn’t.

After fiddling around a little bit, it seemed to work OK but then at some point it would arc but not climb up the wires. For a moment there were some Sparks that shouldn’t have been happening so I quickly and unplugged it and after that I got nothing.

I hope I didn’t burn out the transformer. Can someone help me diagnose this? Perhaps I could check the transformer with a multimeter, but I obviously want to maintain safe conditions. I’d be happy to describe the unit or post photos if that would help.

Thanks in advance.