printing this for my dad, thanks for the tips!
After servicing numerous fans for many forumers here, realised something in common with almost every fan brought to me which is the lack of cleaning/maintenance or utilising an incorrect technique to clean the fans.
1. Cleaning the grille and blade isn't enough, as shown in the photo below, a lot of dust and debris get stuck inside the motor housing causing problems, one being that the motor may become sluggish and the other being that dust blocks the vents at the back of the cover which are meant for air to circulate and cool down the motor. Blocked vent holes means heat is unable to escape and may trip the thermal fuse causing the fan to simply stop spinning. Simple solution is to use a screwdriver to open up and clean off the inside once or twice a year. Some say they don't know how to do it as the oscillating knob is blocking, on kdk and Panasonic fans the oscillating knob is not held down by any screws, just pull with force upwards and it will come out.
2. Using excessive amounts of water in cleaning. Personally i don't recommend washing fans. But if you must do it make sure to let everything dry before assembling back. People put wet blades onto the shaft and causes it to rust, even worse that water will drip into the bearings causing it to rust and make noise. A number of people have perfectly working fan but can't use as too noisy due to rusted bearings. Unfortunately once bearing damaged it is irreversible
3. Fans needs oiling from time to time. It's a moving mechanism after all and like your cars engine, the bearings and motor require lubrication at least once every year. Some people leave their fans unlubricated and it becomes so stiff until it can't move and they think it's spoilt. Also always remember there are 2 bearings im every fan, one in th front and at the rear.