Brett take my advice, the fan needs replacing.
The reason why it was making the noise is because the bearing is worn.
The fans are dirt cheap and only have a limited life.
The fan may slow down or stop without making noise due to the worn bearing and if this happen the CPU will overheat.
It's your choice, replace a fan or you may end up with a cooked CPU.
These CPUs are no longer made.
So if it dies it could be an expensive lesson (Remember when you didn't follow my advice with your voyager)
The following is from
http://www.pinrepair.com/pin2000/index.htm2b. Before Turning the Game On: Check/Replace the CPU Processor Chip Fan
Like all Pentium personal computers, the Pinball 2000 CPU processor has a fan strapped to the top of the CPU chip. This fan also acts like a metal heat sink. This fan is very important, as the CPU chip itself can overheat and "seize".
Although Williams used a ball bearing fan, the fan can fail very quickly. Often after some weeks of operation they need to be replaced. When replacing them remove the foil between the fan and the processor chip. Instead use 'Thermoleitpaste thermal conducting paste'. This white paste is available at Radio Shack in a small tube. Non-working fans can get so hot the metal block had turned light green instead of the original dark green color that came from Williams.
The CPU fan, which can easily fail.
Replace the CPU Fan.
Replacement CPU chip fans can be bought easily in the $5 to $20 range. It's just plain smart to replace this fan when buying a pinball 2000 game, because these fans do wear out, and there is no way to tell "how many miles" an old fan has. So just replace it! For a really nice, high-end model, check out PCPowercooling.com (the suggested model is their CPU-Cool Z1 Skt 7), or from Indek.com (the suggested model is their HDF5010L-12HB).
