I never said it wasn't a great grinder, I had one before I got my Major. I was just giving you a suggestion since you were looking at a K30.. I figured I'd offer maybe a more cost effective option. I don't hate the Super Jolly, the grind quality is great. For cafe use, it's just slower, that's it. I apologize for offending your grinder...
I also never told you to buy a new grinder, simply suggested that you could look at other options as a backup/replacement.
Just a note on retention, the E models of both the Super Jolly and Major have a screen that holds coffee in the chute, and the chute on both the Major and SJ is the same size, the SJ retains about 4 grams, the Major retains about 6-7 grams.. is that really much more waste? For home usage I'd say absolutely, a lot of cafes around here seem to be doing great with it though. In any case.. most of the retention difference is due to the size of the burrs. Of course, if you're pumping out a lot of coffee the retention won't matter as much because you won't have to discard it unless you make a change to the grind since it won't be hanging out long enough to go stale.
Regardless of any of that information, I really don't have any further input as to how to fix your grinder other than contact the distributor who sold it to you in the first place. Sorry.