Bought this second hand Bullet (S/N003514) and found this attached to one of the blades of my exhaust fan.
Is it like for car tires to equilibrate rotation? Or should I remove it?
It’s also on my new R2 Pro, probably for balance…then I wrote this much more to make it to 50.
Interesting that it is placed to one side and not in the middle of the fin. Must have something to do with the higher fan speeds in the new R2 machines compared to the R1 machines 
If I were you, I’d leave it and see what it does and then tell me and the others if we should get one too.
I don’t have it on my R2 Pro.
Adding characters to make it to 50.
Don’t remove it. It is there to balance the rotation of the exhaust fan. You might want to check and make sure, however, that the fan is, in fact, rotating without any wobble or shaking. The fan looks like it needs to be cleaned as well. A short soak in very hot water with either baking soda, or Joe Glo should do the trick. Good luck!
I don’t have this on my R1 machine either. This was posted in the R1 group, so I assume that it has nothing to do with the higher fan speeds of the R2?
Clean? That fan looks about as clean as you are going to get it! It looks like it just clips on. You could try taking it off, and seeing if it spins any differently with it on vs it off. Increase fan speed up to max and see if it appears balanced. I would expect a difference with it on vs removed. Not sure which is better until you experiment.