4 TB IronWolf drive was recognized by Airport Utility, erased and immediately worked fine as a 4 TB Time Machine backup disk.

I took Latimer’s advice and used a 4TB IronWolf drive. The rubber feet from the original drive (2 TB Baracuda) it it perfectly without any trimming. The rubber feet came out with the old drive so I placed them on the new Ironwolf before insertion and carefully slide the whole assembly back down into the enclosure. I used a slow steady rocking motion to ease it back in and the rubber feet went into place at the bottom without any extra fidgeting. From a physical replacement PoV I’d highly recommend the IronWolf, and I have high hopes for it operationally too, but it’s too early to tell about that yet.

I used the tweezer blade behind the wires to pry the connectors out. Slow and gentle, worked fine.

I had to insert a knife between the black and silver tabs to get them to separate.