Time Capsule does not delete old backups.

Unfortunately, when the proposed backup is too large, Time Machine cannot delete enough old files to make room for new backups.

Your options....in terms of most expensive on down.....are:

1) Add another Time Capsule and start backups going there

2) Add a USB hard drive to your existing Time Capsule and start backups going there

3) Erase the hard drive on the existing Time Capsule and start backups over again

Not sure what link you are referring to, since I did not provide a link in my last post.

This link........Verify, repair, or erase an AirPort Time Capsule drive - Apple Support........would probably be a lot more useful though.

Open AirPort Utility

Click on the picture of the Time Capsule

Click Edit in the smaller window that appears

Click the Disks tab at the top of the next window

Click Erase Disk

Choose the Quick Erase option

Click Erase

The operation will only take a minute or two, then you are ready to start backups again. Allow plenty of time for the first backup, since everything on the Mac must be copied over.

Sorry, but you have my steps and you have the same steps from Apple's support document. If that is not working, then all that I can suggest at this point is to get with Apple support.

Glad that you got things working.

After providing the steps to erase the Time Capsule, I guess we took your statement that.......it appears that the AirPort Utility procedure fails to erase the back ups of the old Macs.......at face value.

If you had said that you were having difficulty getting backups going again, that would have been a different question.....and we would have answered differently.