Skipping problems

[monstertooth]

hello i have an older playstation its the
1001 model made around 96
not the one that can do the swap trick
but the machine right after that.
i have said before in a few posts that im
backing up my collection now
that i have a modchip however
i found that some times the fmv skips
like such Need For Speed - Porsche Unleashed
only the opening movie dose it and
only about 5 frames out of the 1:20 movie
i've found that if i play the system for around
an hour or more it seems to play better
then if it's been sitting off all night.
at first i thought it to be my burn.
but i tested it on my computer with psmplay
and it played fine. Im not sure what to do
i think maybe it just needs to be lubricated
seeing as it's 5 years old. But i've also heard
other people talk about len's calibrating
or sticking metal under the lens
so it's closer to the cd. and using black cds.
but i thought it didnt matter what color the cd
was i thought it had to do with reflectivness
and wave legnth. and assuming this is true
why would a cd-r and a original be any different
to the lens.
If any one has any idea's it would be most helpful.