Oops, sorry, me bad. :sad: I assumed you have used it before.
What you should do with ISOBuster is not extract the track, but when you click on the track one or more volumes will appear underneath.
If there is a track with a tiny blue logo next to it then click on that and all your files should show on the right hand side.
Right click again on the tab with the blue logo, and select extract (it should be the top option). Select where you want the files to go and it will extract them.
Then just repeat with all the other tracks, then burn all together onto a new DVD.