Yes, sorry, I should have explained the method - just as you said, I'm doing a backup (library AND settings) on the old PC and then a restore on the new PC.
I can load the local library on the new PC but the problem is, MC still thinks it's on the old PC loading the old local files on the old PC. So it gives its library the name of the old library on the old PC PC. And under "Playing now", it lists the new PC as if it was another PC somewhere else on the network!
I can change the name of the local library to the new PC's name. So then it at least appears to be OK. But then I have two instances of the new PC on the network because JRiver is still seeing the new PC as existing somewhere else on the network. And if I try to delete that second instance, I can't - it just reappears as soon as I hit the delete button. So I think DLNA is very messed up.
What's needed is some way of cloning all the settings EXCEPT the media network/DLNA settings. Or failing that, is there some way of deleting all the media network/DLNA settings? Then I could replace them with "virgin" settings from a newly-downloaded copy of MC, or let MC generate new ones for itself.