Thanks! Looks like there are a lot of special tools needed. Any idea where I can get them? They look expensive.
Expensive? Well, you just got a $1,000 saw for free, so you're way ahead of the game already!
If you Goggle "Stihl specialty tools" you'll come up with several threads -- here's one that I started not too long ago: http://www.arboristsite.com/community/threads/specialty-tools-needed-stihl-028-038-070-090.304611/ You certainly don't need all the tools on this list. I just completely tore down a Stihl Contra (predecessor to the 070/090) and the only specialty tool I had to use was a small gear puller. I have a case splitter, but it came apart without using one.
Two other tools that really come in handy -
Ratcheting screwdriver with kung fu grip - - it's actually a pistol grip, and it makes taking out stubborn screws 100% easier because you can put some real torque on them.
Impact screwdriver - https://www.amazon.com/Lisle-29200-Hand-Impact-Tool/dp/B0002NYDRG - be gentle with this one so you don't crack your case.
And some REAL penetrating oil - Kroil - https://www.amazon.com/Kano-Aerokro...UTF8&qid=1487568481&sr=1-1&keywords=aerokroil - 100% better than WD40 and much better than PB Blaster.
No need to be intimidated by the rebuild, either. These are fairly uncomplicated saws. Just take lots of pictures while disassembling and use the service manual and the board here for reference.
Good luck.