Thanks! it is more clear now. I will give a try this weekendWrite Mark's image to a sdcard and then boot it. Go to openELEC settings in the right pane press down until you see the option "Create System and XBMC backup" choose it, wait till it has backed up. Then connect to the RPi using winscp and find the backup folder inside there is a backupfile.tar copy this to the PC.
Use this guide to make a clean install. Then winscp to the clean setup copy the backupfile.tar back to the now empty backup folder. Go to openELEC settings again and choose "Restore Backup" then choose the .tar file and it will restore Mark's backup to the new clean system.
Instead of winscp you can also grab the file using windows shares if you are more comfortable with this just press leftwindowskey+r the run box will popup enter \\openelec and you will get a list of folders on the RPi amongst them also the backup folder, enter it and grab the backup file. Same procedure to copy it back to the clean install.
Pretty easy. Btw the file will not be named backupfile.tar but thecurrentdateandtime.tar