It is similar to this one
It had worked fine until around 2/3 months ago, when it suddenly started to missbehave. Initially very occassionaly when turned on (using the light switch) it fails to rotate, and only makes a low hum sound instead. The rotor does in fact try to turn, but it looks as if it is under strain and only manages to turn very slowly if at all. When I gave the front cover a tap everything seem to be back to normal for a few weeks.
Unfortunately this is now a daily occarance, and as of yesterday no mater what I do I cannot make it rotate properly again for more than a few minutes/seconds before it stops again.
I suspected that perhaps the cause was that the fan body was slightly warped putting pressure on the motor as the screws holding it to the wall seem to pull it slightly, so a loosened them, but without any luck.
When working the fan seems absolutely fine, so I am a little puzzled as to what is going on.
Any ideas what may cause it other than it being faulty before I bite the bullet and buy another one?
Many thanks in advance.