Unfortunately, this fan was designed to be ran until it wouldn't run anymore, then thrown out.
However, I likely know what the problem is. The motors in these and most other small fans are a C-Frame Shaded pole design, they have porous bronze bearings, with a small amount of wicking material around them. They supposedly are oiled when they leave the factory (the motor factory not the fan factory) What happens is, the oil on the bearing surface is churned around by the rotating shaft and the heat from the motor slowly evaporates it, as this happens, the wicking provides more oil, which soaks through the porous bronze bearing, keeping everything lubricated. Over time, two things happen, 1. If the oil used wasn't very pure (and we are talking a $15 fan here) the volatile parts of the oil will evaporate leaving behind what won't evaporate, therby "gumming" up the bearings, making the blade hard to turn by hand and the fan very hard to start running, but once it gets going, it runs OK.
2. All the oil evaporates out, then the bearing and shaft are running together dry, the motor will run like this for quite sometime as the bronze is softer than the shaft and the metal coming off the bearing will provide some lubrication, but the bearing is being eaten up by the harder shaft. Eventually, the bearing will wear so much that the rotor drags on the stator and the fan will suddenly lock up hard when running and make a loud buzzing noise like hair clippers.
From what I remember, I had one of these that I used to boost the output from an oil filled radiator and when it gummed up, I was going to take it apart and re-oil it, but the thing is held together with security screws which I didn't have the tool to remove, so I threw it out.
However, if you can get in it, open it up, pop the blade off the shaft by pulling on it, motor should be held in with 2-4 screws, get some 3 in 1 oil (in the blue can) and oil both at the shaft and behind it where the wicking is. Leave the motor hanging there, plug it in, run it for a while to get it warm and oil it again, then put it back together and it should go back to working for a few more years.
Answers & Comments
Unfortunately, this fan was designed to be ran until it wouldn't run anymore, then thrown out.
However, I likely know what the problem is. The motors in these and most other small fans are a C-Frame Shaded pole design, they have porous bronze bearings, with a small amount of wicking material around them. They supposedly are oiled when they leave the factory (the motor factory not the fan factory) What happens is, the oil on the bearing surface is churned around by the rotating shaft and the heat from the motor slowly evaporates it, as this happens, the wicking provides more oil, which soaks through the porous bronze bearing, keeping everything lubricated. Over time, two things happen, 1. If the oil used wasn't very pure (and we are talking a $15 fan here) the volatile parts of the oil will evaporate leaving behind what won't evaporate, therby "gumming" up the bearings, making the blade hard to turn by hand and the fan very hard to start running, but once it gets going, it runs OK.
2. All the oil evaporates out, then the bearing and shaft are running together dry, the motor will run like this for quite sometime as the bronze is softer than the shaft and the metal coming off the bearing will provide some lubrication, but the bearing is being eaten up by the harder shaft. Eventually, the bearing will wear so much that the rotor drags on the stator and the fan will suddenly lock up hard when running and make a loud buzzing noise like hair clippers.
From what I remember, I had one of these that I used to boost the output from an oil filled radiator and when it gummed up, I was going to take it apart and re-oil it, but the thing is held together with security screws which I didn't have the tool to remove, so I threw it out.
However, if you can get in it, open it up, pop the blade off the shaft by pulling on it, motor should be held in with 2-4 screws, get some 3 in 1 oil (in the blue can) and oil both at the shaft and behind it where the wicking is. Leave the motor hanging there, plug it in, run it for a while to get it warm and oil it again, then put it back together and it should go back to working for a few more years.
Hope this helps :)