Sorry for replying into a old topic but all you will achieve putting an HD7 laser in any PS2 older than V5 (V5 was the first model to support HD7 lasers)
If you use lenschanger on anything older than V5 will give you a corrupted eeprom.
Using lenschanger on newer consoles (75000 and newer) will also give you eeprom corruption. Remember to AWAYS BACKUP THE EEPROM before using lenschanger so you can return to a known state should it fail.
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...)