Can you please, show the method you used to clean the blade? I have a pair of them in the same sorry conditions.
Thank you in advance.
I have several methods to clean the plates on saws. If I am trying to remove rust from and plate that has an etch on the blade, and I want to preserve the etch, I use WD-40 to soak the rust on the plate. I then use a single edge razor blade holder and scrape the loosened rust off with a razor. I sometimes utilize a maroon Scotchbrite pad and WD. I repeat as often as necessary to remove the rust. If the plate is not pitted, too badly, it can usually be saved.
I have, also, used an electrolysis method to remove the rust. You can Google this method and it is easy to do. I, also, use this for refurbishing rusted plane bodies.
If the rust is not too heavy I use a Boeshield product called Rust Free. It is a weak Phosphoric acid product that does an excellent job of removing rust from any metal. I use this product on everything from cast iron table saws, to hand tools. There are probably other products using Phosphoric acid that may be more readily available to you locally.
Getting the heavy rust off is just the start. If a plate is pitted then you have to get into the pits to get the rust in the bottoms. If you don't it will eventually come back. This is where the electrolysis method shines. Chemical treatments don't always get it removed.
Once the rust is gone I sometimes sand the plates, using progressively finer grits until the plate is smooth and usable ( I refurbish my saws and planes to use...I do not collect!).
Once the plate is usable and the handle cleaned, I reassemble and resharpen and re-set the teeth as needed.
I have salvaged some really nice $1.00 garage sale saws into some fine usable saws.
Hope this info helps