I have an older P89 and haven't shot it in a quite a while and just noticed small signs of rust around the rear sights. Not heavy rust , just the color like it may be under the sights and trying to seep out. I just sprayed the sights and it's set-screw with PB Blaster penetrating oil and I am going to let it sit for 5 hours. What size is the set screw and how do you guys get the rear sights off ? I dont have a vise and I want to be as gentle as I can. Thanks for any help.