It's the worm drive and sticky sled that the laser rides on. Bit fiddly but usually fixable.
sharp ms702
June 2021
got one of these myself and only encountered the utoc error a few days after leaving positive feadback. I imagine that the seller was not even aware of the problem. Using the "lens cleaner MD" from TDK has helped a bit, but I still get errors and makes recording quite scary as I could lose the whole disc due to one utoc error.
Gazza
February 2010
have you tried a new disk?
kb
February 2010
I can answer this question...
I have a sharp ms-702 and it comes up with toc errora?