I would try renaming the ~/.kde4/share/config/plasma-appletsrc file, then regenerate the file by setting up your panel again.
I has a quick look at the contents of this file yesterday, and noted the applet positions seem to be stored in geometry setting like this:
Quote:
[Containments][73][Applets][88]
geometry=1194,3,64,32
immutability=1
plugin=digital-clock
zvalue=0
|
So it might be feasible to experiment and hand-edit the relevant sections if preferred.