My daughter has the first gen Macbook Early 2006 and it was getting hot and shutting down and the optical drive had stopped working as well. Took it to the GenusBar and was told it was an antique and they wouldn't even attempt a repair on it.
So off to iFixit I went. Got the parts for about $200 (fan and drive) and in about 30 minutes had them both swapped out. All went well even on this old machine. Very happy daughter.
Don't attempt a repair without the proper tools especially on an older unit as everything is fragile and needs tender care.
Thanks to iFixit for the great repair instructions and availability of tools & parts even for our antique.