Glad the gun is fixed.Update: I was contacted by Joseph Zakher. He offered to send me a new cartridge stop and new action slide (pump slide assembly) if I was comfortable breaking down the firearm to install the parts. I said this was my first gun and it looked like a bit more disassembly than I was comfortable doing, so they sent FedEx to pick it up today. Hopefully the turnaround will be quick.
Thanks for the advice here, all.