Oh, this means general read-problems as well. Lens cleaning! If you like to, you can do the following (this is how I described the way I do it to another member ages ago):
Open the drive very carefully. Clean the lens with newly bought isopropanol 100% on a Q-Tip from a new package. Never push the lens down or to the side with any pressure at all! Just let the wet - but not too wet! - Q-Tip slighltly go over the glas. The isopropanol 100% will do its work. Repeat the process one or two times, since without pressure the isopropanol 100% has to do all the cleaning work with it's cleaning power alone. Then close the drive very carefully.
You can get isopropanol 100% in the drugstore/pharmacy. Tell them that it has to be 100%! Oh, and don't be confused, when they tell you that it's 99.7% only. This is only because it's impossible to make 100.0%.
Thats it. Following these steps closely will give you 100% safe and effective cleaning plus big money saving by costing around $2 (new Q-Tips + very small bottle of isopropanol 100%).
It's a SATA drive, so bad cabling is not the problem here I guess. But it doesn't hurt either to plug the SATA cable in firmly on both ends after lens cleaning. You can also try to swap the SATA cable to another one. But that won't help I guess. The lens cleaning is what makes me confident. The guiding track of the laser-pickup can also be cleaned from grease and dust with isopropanol 100% but you then HAVE TO reapply special grease like that. And I don't know where to buy some of that high quality and one that is used for laser-pickup guiding tracks of ODDs in general.
If someone knows that, please help. Thanks!