My wife has a hand-me-down Epson XP-610 inkjet printer. It told her to
replace one of the cartridges but we cannot find the appropriate part
number.

This printer has 5 slots for cartridges. From right to left, the slots
are labeled PBK, M, Y, C, BK.

The BK slot is twice as wide as the others.

What is the Epson part number for the BK cartridge that goes in that
double-wide slot?

Thanks.