What a great buy! I have a 99K with the round bobbin in a similar box. And look ..... you even got the key with it. How great is that! You can see why people tie them on a shoelace (or whatever!) and then tie it to the lid. They can get lost so easily. I found an old luggage key that worked for mine thankfully. Once it's cleaned up and rewired (yikes on that wiring!), you will be glad you got it.