OK.  I found a great post in the Dell forum (sorry I lost the thread) that referenced this Dell YouTube video, (whose link is below) with step-by-step instructions for the deep clean uninstall of SupportAssist, reboot, and reinstall from the SupportAssist webpage.   I carefully followed the instructions.  Not all the items shown to delete in the registry etc. were present but they imply IF they were there delete them. Now all is working!!.  Thank you Dell Community and Dell. Dell SupportAssist Not Installing (Official Dell Tech Support) - UPDATED - YouTube
I have used SupportAssist on my Vostro 7590 for some time, but it has stopped working, won't look for updates (always at 0%) , and provides a message "system is busy, try after some time."  It's been doing this for several days now after dozens of attempts to use. I've seen discussions that show a much newer version than I have.  My version reports it's up to date " SupportAssist is up to date.  Version: 3.14.0.91". My service plan expired some years ago, but I was until recently able to use SupportAssist to update drivers and use all the tools it offers. Now I did have a problem that I had to restore the image from backup and Im wondering if that has something to do with it. In any case, would you have any thoughts on how to get SupportAssist running again? thank you      
SupportAssist is Not Working....Always "system is busy, try after some time"