To solve this issue in an expedited manner, you may need to use a third party free utility called nexusfont.
This software is produced by XILES (http://www.xiles.net) and is free to use even in an enterprise environment.
Curent version of NexusFont can be downloaded from here: http://www.xiles.net/download.php?file=NexusFontSetup2.5.8.exe&product=NexusFont2&ver=22.214.171.1242
Once nexusfont is downloaded and installed, search for the blocked font files in the search box located on the upper right side of the window. Rightclick and choose "properties" from the context menu to make sure that the discovered fonts have the same path as the ones to be unregistered. Once you check the path, rightclick again and choose "uninstall" from the context menu to uninstall the font, A few options are shown (Uninstall and Delete font files, Leave Files where they are, Uninstall and backup font files). Choose the option that fits you the best. Please note that it may be necessary to reboot the core in order to be able to remove the font files (a best practice is to archive them in case you may still need them).
At this point the issue that was impeding on your core repair is fixed and you can attempt it again.