For those of you with DRE's, this is the FAQ on opening up the PS2 that I've used for a couple years now. It also helps that one of the small game shops here used to do fixes on systems and I watched the guy opening up NUMEROUS PS2 and Xbox systems. Of course, I've been opening my systems up since the Genesis AT LEAST.
Here's the FAQ I've been using(great for older model 'fat' PS2s):
http://arstechnica.com/articles/paedia/hardware/ps2.ars
While that FAQ above shows you how to open your system and adjust the height wheel on the PS2, I'd only recommend the height adjustment for the laser as a LAST resort, as adjusting it too high can cause disc scratching and the laser to burn out QUICKER.
Simply use that FAQ as a guide to get the laser cover off and use a q tip moistened with rubbing alcohol to clean the lens. Then, follow the steps in reverse to close it back up.
Make sure when you open your older model PS2 that you mark down where each screw came from, so you don't accidentally put a long screw in a short screws hole and right through the motherboard.
Also, if you want a really CHEAP way to get all that dust from the 'grill' under your controller ports and disc tray, try gently inserting a soft bristle toothbrush into the grill and gently turning it towards you.
Here's another point that should save MANY 'screwed' PS2s from occuring. You know that silver ribbon cable that connects the reset/eject button assembly to the rest of the PS2(and the 'lid/top' of the PS2 to the rest of it)?
That can be simply re inserted gently under the right side of the PS2 from the perspective of the disc tray facing you. All you have to do is look for the proper slot/opening it goes in. Voila, no more screwed reset/eject button. I'd definitely suggest borrowing a gf/wifes tweezers for the delicate job of re inserting the cable though, as it's frustrating without the proper tools.
Of course, if you want an EASIER way to avoid that problem altogether, try sliding a flathead screwdriver up under the SIDE of the button assembly which is kind of a snug spot and GENTLY push up on the screwdriver. With enough pressure, the button assembly will 'pop' out of the 'lid' of the PS2 and you can put the top of the system off to the side and not need to worry about messing up the reset cable again.
I've taken at least one PS2 down to base components before(I'm talking like ALL APART) and I put it back together and it still worked. So, I'd like to think that I have SOME experience with these things.
BTW, if you hear a grinding noise, that's possibly the laser scratching your discs. A rubbing noise when the tray is going in or out of the system? That's because all of the lubrication on the tray mechanism is dried up/gunked up.
The same can be said if you hear a clicking noise when your PS2 is trying to read a disc, as the rails the laser slides on may be all gunked up. If you open the PS2 and see white lumps of something on the silver rails the laser slides on, wipe that off there and using a lint free rag or q tip, moisten the rag or q tip with a silicone lubricant and generously(not so generously you see it dripping off the rails) re lube the rails.
As far as burnt out or malfunctioning controller ports go, they're readily available on many sites for as cheap as $5 and as much as $18. Most sites will offer free shipping with the $18 ports. Although, most times all a system needs is a little tlc to get working again and doesn't even NEED a replacement part.
Here's at least one site I've seen replacement parts on, but I'm sure you guys and gals can Google some more, right?
www.richspsxparts.com
Of course, if you're too afraid to take apart your own system, you could pay Sony to do it FOR you. It's 'only' $45 for a replacement(refurb system) or $75 for repairs to yours. Their number is 1-800-345-SONY.
Good luck with all of your repairs, my fellow CAGs and I certainly hope this info and link to the FAQ I've been using all along has helped you in some small way.
Oh and anyone with a 50001 model PS2 doesn't even NEED to worry about the reset/eject cables, as they're part of the main set up of the system and not attached to the top of the system anymore. Just be careful taking that top part off.