I believe this is simple fix.

I thought all fans come with small weight that you can stick on top of any blade to balance the fan. You need to experiment where to locate the weight.

I'm presuming it was not mechanical sound but humming sound like electromagnetic or or transformer in power supply.

This normally due to degraded capacitor which functions as to rotate the fan blade. If the capacitor becomes totally bad, the fan won't turn. This capacitor can be bought probably around RM6 in electronics spare part shops. Sending for this kind of capacitor replacement will cost around RM60~70 I think.

Over the years it will become bad. That is why old fans usually make this sound

Yes, a bit is normal unless it bothers you and you want it to balanced.

I remember most of my fan come with black square about 4mm thickness weight. You suppose to stick it on one of those fan blades to remove wobble. You need to experiment to find on which blade and at best location. I never used one anyway. The wobble just very slight only.

My latest fiber type blade of Panasonic fan has none, stating that the fan is precisely engineered to be balanced when installed the blade properly. So, no weight required and it was well balanced as stated after I installed.

I see. Never had 3 blades one before. My Panasonic with 5 blades (it was said fiber) has no weight either since it is said to manufactured it precisely. So, weight is not required.

I think it has nothing to do with expensive or cheap. It is just what the manufacturer think how fast the rotation should be at each speed setting. This depends on what capacitor value they decide to fit in.