You probably got the laser unit coils burnt with the read error problems you were having before. If you insist in unsing that laser you will probably get your BA5815 burn also.
My advice is for you to look for assistance of a pro.
You can check the impedance of the lenses coils with a multimeter on the X1 scale. They should measure arround five OHMs on both coils. There's a pair. One does focusing (Up and down) and the other does tracking (forward and back, on the same direction as the motor that moves the laser) for the lenses.
What damaged your laser coils was the low adjustment you stated before, and you which probably insisted a lot trying to read discs (probably DVDs) with the laser power badly adjusted.
This might be too rough to say "in the face" like I did, but I say that based on the description you gave about your PS2 don't working while laying "flat" on the table. I'll explain why I think your coils are burnt: If the coils are short. the BA will send the same current as usual, but the energy will be converted in heat instead of magnetic propulsion on the lenses. That means the PS2 will have a hard time trying to focus on the groove at the disc. If you have the PS2 on the vertical stand position, the power required to adjust the focusing will be diminished.
I hope this was informative.
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)