The squeaking that is unrelated to worn brakes is caused by a high frequency oscillation when the brakes are just barely to low application. All pads...
So I think you're talking about the webbing between the inside corner of the dovetail and the rail. At the corner that we can see in your photo that...
I have my own small (1 man) custom woodworking business LLC. I have done a mix of work for hire in the shop as well as on site (installation, finish...
Very simple fix. If it was flat with finish on both sides, it will go back to flat with the finish off both sides. Sand both sides clean and stack on...