Successfully upgraded my A1409 to a Western Digital - WD100PURZ - 5400 RPM Class SATA 6 Gb/s 256MB Cache 3.5. There are two additional steps: (a), there is a rubber strip around the original drive that reduces noise and protects the drive, gently remove from the original drive and place on the new drive; (b) once the rubber strip is on the drive, it is hard to get into place, angle the drive towards the connector side, and press in.

Successfully replaced the original 2TB drive in my A1409 Time Capsule with the following 8TB drive: WD Red 8TB NAS Hard Disk Drive - 5400 RPM Class SATA 6 Gb/s 128MB Cache 3.5 Inch - WD80EFZX

NOTE - on my drive that I removed, a Hitachi 2TB drive, there is a rubber band that is attached with adhesive around the edge of the entire drive. This comes off easily… reattach that to the new drive to ensure a tight fit.