Problem With New Laser.

[WiNeOS]

I just recently got a second hand 360 that had a faulty laser which came up with an unreadable disc error when I tried to play games.
I thought a good way to solve this would be to change the laser. Now I just got the laser through the post and have desoldered it and put it in the same way as the other.
The problem now is that I get an unplayable disc error at the bottom instead of the unreadable error.

Anyone have any ideas on whether I've done something wrong or if the drive was already broke?

 

[WiNeOS]

I have tried stretching the spring to see if that was the problem now but still no luck. I've tried original games, dvds and music cds but nothing.
Also I forgot to mention that I haven't flashed the drive yet and I don't think it has been by anyone else either.
Does anyone know of any other ways that the drive can get this error?
I have checked the magnetic washer but it is stuck firmly in place.