Hi from a noob

I have a noisy graphics card fan. My pc is about 18 months old, so I assume something on it is wearing out. I've taken out the whole graphics card and blown off all the dust, it is nice and clean now but still noisy. When I look at it while the side is off I can see it is probably not turning round as fast as it should. If I touch it with the rubber end of a PENCIL, the noise STOPS (and, of course, so does the fan!)

The graphics card is an Nvidia Geforce 8600 GTS.

Can anyone tell me if I probably need to replace the fan? If so, how do I find one that is compatible? Would a Zalman VF900 CU be ok? Would it be straightforward to take off the old one and replace it with a new (is it just a question of unscrewing one and screwing the NEXT on)?

Should I try using some oil first ? And, if so, what sort?

Also, in the meantime, is it ok to keep running my computer or will that damage my graphics card?

I really am not very savvy with computers, so please explain any ANSWERS in simple terms!
Thankyou.With the card out of the machine carefully remove the fan...2/4 screws.
Then bring it with you to a PC STORE to match up a replacement.
I've rescued dozens of vid cards this way.

NOTE: Make sure if the receptacle is 3 prong to replace it with the same...Just wondering...When you cleaned off the dust, did you hold the fan still?

Many fans end up broken because users accidentally get their fans up over 3000+ RPM, which stuffs the bearings in them, and causes them to sound even worse.

Happened to me a few times