Select the startup drive and then choose File > New Image > Image from “Partition Name.”.

When prompted, enter any administrative password.

(Optional) If you have FileVault enabled, select your partition, and click Mount.

Click Disk Utility in the list that appears and click Continue.

To isolate whether it was hardware or the OS, I decided that since the disk was still reachable, I’d perform a full clone via Recovery using Disk Utility. Apple’s safe mode, for instance, disables accelerated graphics, for instance, which can cause video glitches. Apple and other computer makers engage a simpler mode in their graphics system at boot time, and then fire up the full power once the OS has initialized. I began to wonder if it weren’t a video-card or GPU problem instead of a system problem. Without the software installed, something else still triggered this slightly different behavior. I contacted the former developer and followed his instructions to use Recovery and Terminal to remove all relevant files, but that didn’t solve this problem. In that case, the spinner would appear and disappear, but no cursor, and much more rapidly. I’d had a similar sort of problem crop up once during beta testing for software that I don’t want to mention the name of, as the issue was resolved for those of us on the cutting edge and the particular release of software is no longer in development.

To every spinner, turn, turn, turn, there is a reason, turn, turn, turn.

This would recur over and over for hours.

After entering my account password, my Mac showed a white progress spinner that uses “spokes”-the kind of spinner you usually see at shutdown-would appear for several seconds, then disappear, replaced with a cursor that couldn’t be moved with the trackpad. A few days ago, after my 12-inch MacBook running the latest Sierra became sluggish, I restarted.

Imac spinning wheel on startup