by what I know Lenschanger have no real effect on V1,V2,V3 and V4 machines because it uses the earliest DVD-Rom drive hardware which isn't capable of using Sanyo (HD7) lasers. It's still a awesome tool to change/backup the EEPROM on old machines
Also there is several kinds of 400 (Sony) lens
400A is used on the SCPH-10000
400B (type 1) is used in V1,V2 and V3 and it has a small tab for the limit switch.
400B (Type 2) is the V4 lens and it's the most common lens arround. should work on any PS2 you can fit it in even the 10000...
400C (type 1) has white plastic arround the lens and is same as 400B or A electronically wise. Mechanically it's a bit diferent so if you fit it on a old PS2 it might damage the connection flat cable. but will read the discs fine.
400C (type 2) has yellow plastic arround the lens (this one comes on V6s, V7s and V8s)
400C (type 3) seen on 50k units and has "KHS400C" written on the plastic cover. Besides this seem to be the same as the type 2 400C)
Sanyo lasers I've seen a few variations where mostly is what people refer to as "open faced" or "closed face" but they're all the same thing and the laser body can be either metal (older) or plastic (newer ones on 50k units)
This is just to help you to have a idea on which kind of lasers you can use on your V3.
By the way you might have adjustment trouble on your V3 or the flatcable that connects the drive to the mother board has bent pins ... check it ...
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...)