The soft reboot worked, almost.
I can now see the device just as I did before I accidentally deleted it from the list, but now when I try to pair with it, I get the message "Couldn't pair with RDP-XF300iP because of an incorrect PIN or passkey". This is rather odd, because I connected with this device (a Sony RDP-XF300iP radio/iPod dock/bluetooth speaker) many, many times before and never needed a PIN or passkey. I use it as an external speaker for the Xoom. I've checked the user manual for the device, and do not see any mention of a PIN or passkey (which does not surprise me, because I never needed one).
How can I have an incorrect PIN or passkey when the device with which I'm trying to pair does not have any capability for setting a PIN or passkey?