Hi, VisionTek has stated that they will honor their warrentys on their legacy Geforce products. You may want to contact them at http://www.VisionTek.com
If they cannot help you, then you can find replacement coolers from such sites as
Here is a link to a cheap Geforce4 cooler
Im sorry i cant help you on how to remove the heatsink because i have not had a geforce4, however i suspect there should be some mounting pins/screws that go though the pcb that hold it on.
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