The Laser should be a PVR−802W and you can "swap" it.
Unfortunately this is not the "Best" Laser Modell (you can not use another Modell !).
I do not be sure it is a good Idea to replace it with an also used one.
They are cheap (around 11 $ on Aliexpress for Example) so maybe a Replace Laser is a better Idea.
Of course,I understand.
You can buy a unmodded SCPH-77xxx Modell and "hope" the Laser is already good (a 50:50 Percent Chance).
As mentioned,the Laser Type is not the Best,so maybe buying an already "softmodded" PlayStation 2 is also an Alternative (FreeMCBoot).
You can test then maybe before you buy it,with Backups the Quality from the Laser.^_~
I think I may have answered you on psx place. it shouldn't affect the modchip, but sometimes the modchip is the problem (not the laser). I replaced the laser on my original ps2, which lasted about 12 years. after 2 years, it couldn't read anything again. I asked someone more knowledgeable about it, cuz I didn't want to have to replace the laser again. it's not very cost effective then. anyway, he thought it might be the modchip, so I bought a brand new everything, system, laser, and modchip (matrix infinity clone). this system is very fast.
that would've been my option as well, but I have over 300 discs. the discs I tried still worked, so I didn't want the hassle of a new hdd and getting games on to it. since I like to backup things, it seemed like a very insurmountable task. don't know much about phats, but I did own one at first until the laser died. then, I got a slim.
Getting a modded slim would have also been my priorities, but now that I can't replace my current slim and that I am nervous about using a solder gun, that solution is a long way off.
I'm going to get a fat console and start off fresh.
There is now a way to make your own Free McBoot and not have to worry about having to buy it from some freak that sells something that is free (not complaining, but there are sites which offer these services and the only thing you have to worry about is paying for shipping, so it does seem to be boneheaded and low budget) and the instructions are pretty simple.
If you want the link, I'll PM you for it, just PM me first.
Anyhow, now I will not do further bitching, complaining, and will now get on with life.