All About Pocket Knives

I am new to this and learning by doing (and watching video).

I have disassembled an old two blade. It was loose before I took it apart. I think I see why, the spring is about 0.6mm thicker than the blade.

How would you "plane" that spring? I only have a hand held electric belt sanderr and hand tools. I started in on it with the belt sander, but it is about impossible to get that level - the part I am sanding ends up wavy. Small part and comparitively large sander.

I would appreciate any guidance

I have not heard of anyone planing springs (not saying it isn’t done just saying I haven’t heard of it). And I don’t know that you’ll be able to accomplish that with basic tools.
Generally the blade and spring thickness are the same so it’s possible that the blade has been replaced previously.
I’m sure one of the pros will be by shortly to give you a better answer!

There are two springs. They are (at this point were) the same thickness. The smaller length blade is definitely thinner. It was not in good shape when I purchased. May have been cheap to begin with. I may just convert to a single blade. This is my first attempt - I have kind of taken the lets tear into it and see what I can learn.

put it in a vise and file it. Or rub it on a large diamond stone. Are the only ways I can think of.

Good ideas. I will try the diamond stone tonight.

If you thin out that back spring to the same thickness as the blade, the blade will bind between the liners.

Look at the end of the tang and see if there isn't an edge worn off one side of it. There will be a little lip of metal that hangs off one side as opposed to the other showing it is not worn evenly.

The blade tang is not going to wear down like that (in width), the spring is made wider, and the spring is the softer material than the blade tang if it's made right.