Control Center > Disks > Mount (something) usually works fine since it runs as root. You have to enter the path to the usb stick.

secipolla,

Yes, that is easy enough, but how can I be sure that it is unmounted? From what I can see there is no indication that it is really unmounted. No light goes off, there is no message etc. Is there a terminal command that can let me know?
Thanks,
Dave

hmm. This post appears promising.
error-while-trying-to-unmount-usb-drive-t2458.html

Hi Dave. PCManFM unmounts the drive but it keeps lit. As a comparison, Nautilus from GNOME has the"Eject" option and also the"Safely remove" option which turns off the light in the flash stick.
If you unmount the stick with PCManFM, I think data wise it's safe to remove the drive but I can't tell you if it's ok or not for the drive.

Got it! Thank you. Just needed some expert advice.
-Dave