Sorry Tony, but you've obviously never been involved in audio repairs in any way
The fault will almost certainly be the laser/optical assembly, cleaning the lens 'may' produce some improvement but the only real cure is to replace the laser/optical assembly. Cleaning doesn't help much, because you can't clean inside the optics, and those get dirty as well.
I would estimate that probably 99% of CD player failures is the laser/optical assembly - as a professional service engineer you don't look for anything else first, you replace the laser assembly and then do further tests if that doesn't cure it (although it's pretty well certain to).