ps2 slim still wont read cds right after i replace the laser

[nintendokid]

ok ps2 slim 90001 silver wont read any cds or dvds i replace the laser 2 times but it still wont read.

what part on the motherbourd do i need to look at.

the disc spins but wont read, start up menu comes up, but its not reading anything. and no this system dont have modchip. so pls dont comment about that.

just tell me on the bourd where i need to look at, i also try the ribbon cable thats for the laser but that was not the problem the repair man said.

so im lost plus that man was a jerk the repair man i maen.

help me somebody.