I don't know how many I already brought back to life, tons. Basically ALL fans go 'put at some time. (Talking about after some years or so).
Nice instructions, doing the same thing, just be careful not to lose the small rubber rings and the washers when you open up the fans.
Take the entire thing out, clean the axle and the hole with 96% alcohol. Clean everything, also the washers, and of course the entire fan, blades etc.
Put it back. One drop of sewing machine oil on the axle/hole. Put the final ring and then the washer back (note the order there, the rubber goes first, then the washer), then the nylon clamp ring and then put the cap on and the label. Done.
The entire thing to do is easy and effective, not even a reason to get new fans really. But in my case (PUN!!) the problem was not so much fixing the fan, but mounting the fan back on the HSF with zip ties. The GPU was blocking access there so I had to take out the GPU. Since the HSF was also dirty I took the opportunity to take out the entire HSF, which of course also meant applying new MX4 on the CPU etc. I always hate it when something which SHOULD be simple and only should take 2 mins turns out some major op
Anyway...not sure whether Vaseline or sewing machine oil would actually be better, this time I used oil since the old fan was all greasy, I might actually have fixed this one (a Scythe) before once.
** As for fans with ball bearings...what you can do there is to put the bearings into alcohol....leave them in there for a while and later dunk them in oil. Just an idea.
*** Edit 2: In your PC bios, keep the setting activated where it monitors your FAN speed. Otherwise you will never know when your fan actually craps out! The BIOS and it sporadically reporting that the fan is not turning ("CPU FAN ERROR") or turning slower than it should as it happened here is also a sign that the fan is going and needs to be replaced or this fix.