Symptoms of Failure
Our problems started with Time Machine backups starting, but not completing. We were also having difficulty shutting down. When I dug deeper, I had similar problems with the sparse bundles in Disk Utility. The problems went away when I switched Time Machine over to a different hard drive.
Our backup strategy called for hard drive cloning every two or three months with Time Machine for incremental backup. I considered staying on the external drive, but it was an effort to even get a weekly backup on the external drive. And the Time Capsule is so nice when you have laptops. This was also an opportunity for me to upgrade to a 1TB hard drive.
The repair went smoothly with an assist from the internet. Brandon Hansen’s Hard Drive Repair for Time Capsule was particularly helpful. If you are comfortable installing a hard drive or card in a computer, then you probably have all the skills you need.
After Action Report
My fan power connector was found disconnected during the repair. I may have done it myself during the disassembly, but I can’t help but wonder if the problems were caused by over heating after the connector came loose.
I had no problems accessing the old hard drive using my USB hard drive adaptor. Disk Utility reported a bunch of errors when repairing the sparse bundles, but was successful in the end. I don’t expect to need the old data, but I’ll keep it for a few months just in case.