Cleaned and lubed doesn’t matter. A lot of the Interarms Walther PPK-Ss had manufacturing problems that resulted in the barrel and ramp not matching up properly, causing jams no matter how much lube you kept in the area.
I have an earlier one that jammed until a little machining was done, I’m guessing you have one of the later models where they corrected the problems. If you’ve never had jamming issues at the ramp, you’re lucky.
I hate to admit this but the Walthers made in Germany (and France) are better quality than the U.S. made ones.
bought new in 1987, but I get your point.