If you can, replace the recoil springs
One weakness of the P38 was that the slide can develop cracks in the area of the locking block recess.
My first pistol was a P38. For many years, I shot that pistol almost exclusively. I fed it huge amounts of WWII surplus, plus some handholds. I never changed the recoil springs. About 1990, I was oiling it up after a range trip, and I noticed a crack running up the left side of the slide. I knew the importer, and they told me I should have been replacing the recoil springs periodically. I replaced both the springs, and the slide.
If you examine the P38, next to a Beretta 92, the mechanical similarities are striking.