I had asked a few servicemen and all I got was a short "...there's an internal thermal fuse...". I trawled the web for months but just could not find any info on where the fuse was and how to replace it. Finally I decided to sacrifice one of the fans and dissected all the wires going into the windings.
From this came the schematics of the fan, but only up to the motor windings.
This instructable comes in 2 parts: (I)Troubleshooting and (II)Fuse replacement.
Step 1: Materials Required
Flat tip screw driver
Scissors or Pen knife
Soldering Iron and some Solder
Some string about 0.5mm in diameter
Spare wire, about 60cm long
Capacitor 1.4uF 450VAC (if required)
Thermal Fuse 130degree C, 1A, 250Vac
(note: I could only find a 2A 130deg replacement @$1.50SGD a piece from the local electronic component shops. Sorry I don't have equivalent part number from Mouser, RS n Digikey)