I'm hearing weird fan noises on my X60 tablet sometimes. It's a buzzing noise, somewhat like fan blades hitting a sheet of paper. The noise isn't always there: If I screw down the keyboard very tightly, then it occurs all the time. If I don't, then the noise only appears about once a month or so, and when it does appear, changing the orientation (e.g. lifting one side, etc.) of the laptop will make it go away; putting the laptop back in its original orientation and the noise resumes.
Can anyone shed some light on the situation?

The fan is only 'hanging' in there, held my electromagnets.
It's probably worn out after so many years (i.e. magnets got weaker) and there is up&down 'play' on the fan-axle.
Replacing the fan will sort it.
But if it's only 1x per month, who really cares?

Well, I may get a new fan nonetheless.
Does anyone have experience with brand new Lenovo fans? Are the "new" fans from China really new and trustworthy? I see some description of the new fans mention that they come with thermal grease already applied on the heat sink, is this really the case?

New and Genuine Lenovo fans are available, but can be a bit pricey unless you buy large quantities in bulk. Some of those listed as "New and Genuine" from China are probably the real thing, and some probably not ...

As for the thermal paste provided or pre-applied with fans sold online, including that which may be supplied with New, Genuine Lenovo fans, it's usually of an inferior quality. Get some Arctic Silver 5 Thermal Compound, which is very good quality stuff. It has always served me well. One small (3.5 gram) tube doesn't cost that much, stores well, and will service many laptops. Why go through all the trouble of changing out your x60 Tablet fan (and, yes, it's a bit of trouble- take it from someone who's changed out many- it's a bit of a delicate operation, the fan on these models being partially covered on the back side of the system board... Take off your gorilla gloves and be gentle, Charles ) ... Why go through all the trouble and then lose efficiency/have poor conductivity with a poor thermal compound?

Have a good day,
Daniel.

Well, actually I'm currently in the position of buying stuff in China, so cost isn't that much of an issue, as long as I have a way of telling whether a fan is indeed genuine or not. A simple search on taobao.com turns up new fans at prices around $30. Unfortunately Arctic Silver will be more expensive here than in the US...
Also I've already taken the machine completely apart a few times. When I first got it the fan noise was much louder, so I took the fan blades off and applied a drip of sewing machine oil to the axle. Also replaced the old thermal compound with Arctic MX 3. The machine runs at ~ 60 degrees Celsius when browsing, which isn't bad IMO.

I have this same exact effect, and I can essentially completely work around it, with Thinkpad Fan Control utility.

I can stay under 55C for a good chunk of time, without the fan running at all.

Have the fan set to the lowest setting, "1" and lowest rate about 2300 rpm. You will barely be able to hear it, and it won't speed up and down hunting. I can still hear the fan noises on startup, before the fan control utility is loaded.

For me the fan control utility manual setting at 1, solves it.

Bought a new genuine fan and replaced the old one. Well, there's actually a bit of story behind this.

The original fan is a 42X3804 Toshiba fan, with a metal fan casing and a straight arm between fan casing and CPU heatsink. I bought a supposedly genuine Toshiba fan on taobao first, but when it came in the mail it was obvious that the GPU heatsink was bent out of shape and would not fit, so I returned it.
Then I bought from another vendor, this time a 42X3804 Panasonic fan. It has the same FRU but different construction: the fan casing is plastic, and the arm between fan casing and CPU heatsink is angled and wider. This time the fan looked good, so I replaced the old fan with it. There was some factory thermal compound already applied to the heatsink in small dots, but I wiped it off and applied some Shin-Etsu 7783 also from taobao.

With the new fan, temperatures are similar to before, hovering between 40 and 60 Celsius. I have yet to hear that weird noise, but only time will tell whether it's really fixed or not.

It is the power wires that go into the fan, the fan blades hit them. I had the same issue on my X60 Tablet and my wifes X60s. Pulled the wires off a bit and secured them with the tape.
It happens more often with keyboard tightened to the max because the three small pads are pushing the fan housing with wires closer to the fan blades. If you remove these three little pads then the noise will disappear also.

So the old fan isn't broken eh? Then I just wasted a bit of cash. Oh well, thanks for the info.