maintenance

As the title suggests, I believe my rear sight screw on my PPK/S is stuck. Its a headless screw and I’ve used both the hex wrench provided with the gun and my own set and nothing seems to turn it. Should I continue to mess with it? Should I use oil to loosen it up, or should I just play it safe...

Been keeping mine in an egg-foam plastic case inside of a gun sock, light Hoppes oil all over. For some reason, I just had sudden spots appear around the barrel end of the slide (also around the lettering) that do not rub off. Is that from shooting or am I doing something wrong in the storage...

Testing out the polling feature, and wanted to see what cleaning product is typically used.

I'm wondering if anyone has any suggestions or experience on long term maintenance for the P99. I've had mine 8 years now and I have about 5000 rounds through her. She still looks great and I haven't had any issues. Any input is welcomed. Thanks