I bought this model as a complete "unconfirmed" set that came with the dock and matching remote for under 3000 yen!
As soon as I fired it up, I could tell what was wrong... watch the video and listen to the horrific sound, but it was evident that it was a gear issue. Luckily I had a spare and was able to replace it!
Please watch the video for the exact steps!
Now that I also have another "bad" gear and gearshaft in hand, I may try the "Loctite trick" that a viewer on YouTube mentioned! I'll keep you posted once I try it!
Thanks for reading and watching!