HOLY CROW YOUR BACK, MY APOLOGIES TO YOU. Most of the time they never return & let us know what happened ?
Ok if they marked the inside probably with Dykem blue ? they didn't mark EVERYTHING ? I MEAN EVERYTHING.
The whole barrel, the slide tabs, inside the slide, firing pin, locking block, everywhere there's a contact point on the gun.
Mine was racking with a slight roughness to it, had a heck of a time figuring it out. It ended up being the small cups on the firing pin. I had to chamfer the edges with a small file then fine sandpaper.
For some reason the 1 cup was sticking out, not sitting tight in the slot, so it was rubbing on the plastic liner inside the channel.
I'm telling ya take a marker color the whole inside of gun (contact points) rack the slide about 10 times and see where it rubs off, gun must be free of oil and grease though.
If it doesn't show with 10 racks, rack it some more or actually shoot it a few times to find out where it's rubbing off.
Good Luck & PLEASE LET US KNOW HOW IT TURNS OUT.
3 out