Cambridge Audio 840-C cd- problems

Hi all, I have a Cambridge Audio 840-C c-d player. It is around 4 years old. Am having problems with it recently. Sometimes it will not read a c-d right away, a message says "no play" but after trying it a few times It will work. (These are not burned c-d's) But then while playing for a while, the audio will stop, and then start again, exactly where it left off. Does not skip or jump ahead as sometimes happens with a bad c-d, or dirty lens. While the audio is blank, which only lasts about 2-3 seconds, you can hear the laser mechanism making the sound it would make if you where to, for instance, change tracks, or when you first put in a c-d.
Any ideas what might be the cause of this? Where I might send it for repairs? Is it worth fixing. Thanks so much

Gary