Course to Course restore fails

Hi,
using Moodle 2.3.3 and trying to import items from one course to another times out.

I also did a backup of the donor course and tried to restore the relevant parts into the second course and that also times out.

Turned on debugging and this was the error...
Fatal error: Call to a member function is_checksum_correct() on a non-object in /home/lisacherney/6figureuniversity.com/forum/backup/util/dbops/restore_controller_dbops.class.php on line 99

Any ideas where to look?

Paul