I don't mean to take over the thread, but here's just one more. I just worked on it today.
A while back
Jack Black
sent me a box of knives that needed a little "fettling" including this William Rodgers Jack with horn handles and worn blades.
I kind of hated to remove a lot of steel, but the pen blade blocked the nail nick on the main, so it was nearly impossible to open. I went ahead and ground away, and the main blade is perfectly usable now. Unfortunately, the nail nick on the pen blade is cut too shallow to get any purchase with my thumbnail. I'm not sure what to do about that, but at least it's out of the way.