Today we restored a course from a 1.6.9 site to a 1.9.8 site.
First we disabled user data for forums as mentioned in
MDL-15489 in order not to get a "Could not restore modules!" error.
After the restore the grade book was ok, but the course scales didn't show up.
In fact the course scales were visible in a completely different course, the course with the same course id on the target site.
This is due to a wrong courseid in mdl_scale. For some reason the original course id was not replaced with the new course id on the target site.