HELP Sony cd changers are skipping

Hello, I need HELP!
My Sony ES cd changers are skipping right
around 4-30 seconds into playing ALL cds.
First, what could be causing this
to happen?
Second, can I fix this, rather than take it
to a dealer and wait 2-3 weeks to get it back,
and get charged a ton of money?
Third, does anyone here have a Sony Service
manual, that I can use IF I can do this?
Forth, I know someone on here had the same problem
like 2 months ago, but I can`t find the thread.
They fixed it by using WD-40, can WD-40 be used
to correct this issue?
The model of cd changer is a CX90ES, or CX70ES,
or a regular CX270.