Thanks to suggestions from the list. Here's what I've done to date, and what I've managed to get to work. 1) It turned out that using Clonezilla to image the whole disk was a good idea. After a couple of tries to install Linux Mint 18 with "grub install failure", I tried turning off secure boot, but realize now that I may not have saved the changes. In any event, the next try to install failed. Then a reboot gave a Windows failure that "automatic repair" could not fix, and machine was only bootable with live USB, which Clonezilla allows. For information, the Windows recovery USB I made failed to work at all. Duh. 2) Recovered disk using clonezilla. Interestingly, Win10 then booted but wanted to do a major update, which I let it do. This added another Microsoft recovery partition. New version of Win10 boots fine. 3) Turned off secure boot. Win10 boots OK (seems to be slower??) but interface screens slightly different in design. Possibly intentional by M$. Then used Win10 Computer Management tool to shrink Win10. This was not nearly so tight as gparted allowed before (50G, now 230 G approx). Tried defragment then shrink and got an additional 8 GB. Not worth the time. Then installed LM18.3 and it installed fine and rebooted OK to Win10. Shut down and restarted using F12 boot select and got a menu that allowed "hard drive" and LM came up fine. Setup allowed change of boot order (but nasty warning that machine could become unbootable). Now can use F12 and select Windows Boot manager. So this appears to not be using grub based on appearance of menu, which has some Dell diagnostics etc. In any event, a workable situation, even if non-ideal (i.e., too large Win10 partition, not keeping secure boot, and non-automatic setup). For promotion of Linux, easier setup for non-geeks is really desirable. I still have to check everything works (cameras, sound, suspend, bluetooth, etc.), but suspect most stuff will be OK from the LiveUSB version. I'll try to remember to bring to next meeting. Cheers, JN