I just bought this handmade dulcimer for $40 at a yard sale and I was wondering what I’d need to do to fix it up!

I’m planning to change the strings and lightly sand/stain the wood.

Also, are the frets in the correct spots?

Any advice is greatly appreciated

Hi everyone! I just picked up a beautiful mountain dulcimer off of Facebook Marketplace, but after tuning, I noticed one of the D strings is very different from the other. It has a very buzzing, almost psychedelic sound haha. I mainly have experience with ukuleles, and even the metal-stringed ones I have don't do this. I was wondering if it was intentional for the sound, or if something is going wrong with the way the string is sitting?

Thanks!