Two things to look at for sure.
First, look to see if the pistol has high profile fixed sights with white contrast marks on the face of the front and rear sights.
Second, look at the logo on the left side of the pistol slide.
If it reads Carl Walther Waffenfabrick Ulm/Do
Modell PP Cal 7.65mm with the Walther banner logo to the left of the inscription then the pistol is most certainly not Pre or WWll manufacture.
It is a post war pistol and thousand were imported recently.
Value is about $250.00 with a spare magazine.
A pre or wartime PP will have low profile sights and the slide inscription will read:
Waffenfabrick Walther Zella Mehlis (Thur)
Walther's Patent Kal 7.65 m/m
Values on these pistols varies wildly due to several variations but on average $400.00-$750.00 is a ballpark figuring for average specimens.
I don't know how anybody would know there is a "Microscopic fissure" at the muzzle unless they had the pistol screened bya microscope and if you can afford to do that you can afford to provide a replacement shooter barrel, along with the original barrel, at the time of sale.HTH