Tool Box Cleanup

I dug out my Father-In-Law's old machinist tool box that he made MANY years ago and my wife wants me to clean it up so she can use it for something. I'd like some suggestions on how to clean it without stripping it. I wiped it with some alcohol and nothing much happened other than some dirt coming off so not shellac. My guess is it's finished with some kind of varnish as it was probably made well before polyurethane was available. The lid will need some TLC and repair and there is some inlay that has started to peel slightly. I think I can manage that. Just want to clean it up to make it more presentable. Internet search was not much help. I'm confident the brain trust here will be. Thanks in advance.

A picture or two might help every one come up with some good solutions
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I know the luthiers of the world use lighter fluid / naphtha to clean instruments without trashing the finish...

Yeah. Naphtha or Ronsonol (lighter fluid for lighters, not charcoal) is probably the strongest degreaser you can use that won't harm the finish.

The furniture restorers I watch use Krud Kutter to wash the pieces first. Home Depot, Lowes sell it. I have used it to clean old machinery for restoration.

I cleaned my father's old Gerstner Chest will Naphtha and a white scotch-brite pad

Sounds like Naptha is my solution-actually solvent-of choice. Thanks.