AD-7241S and AD-7261S having trouble reading DVD

I have had the 7241 for 2 years and the 7261 for a year. They are both displaying similar symptoms yet different machines.

Both drives have difficulty read DVDs I have written on Verbatim DVD-R discs. I can hear the drive heads moving and the drive spin up 5 times per disc before the drive identifies what kind of disc is inserted.

I have also tried some TDK DVD+R and Memorex DVD-RW which seem to fair better with the heads moving only 3 times before the drive picks the disc up.

Writing is no problem once the drive has identified a blank disc, using the built in Win 8.1 burner/verifier.

Did I get a bad batch of discs or are the burners on their way out or is it something as simple as lens dust? BTW CD’s seem to load with 3 head movements too and burn ok once they have loaded.

Hope I have been clear enough in my explanation.