2002 nisson maxima cd player skips and I have been?

2002 nisson maxima cd player skips and i have been using the Phillips cleaner cd which seems to improve it but still does not play without some skipping. i've run the cleaning cd probably 10 times.

also most of the time the left channel plays fine with both the radio and cd but once in awhile i get nothing but static from the left channel.

this is a Bose stereo system that came with the new car, i didn't use it much and i guess i should have been cleaning it all along.