Balancing the cooling fans?

[Mutley00]

I noticed one of the fan blades has a window strip clip attached to it.

Before I removed it, I noticed that the inside of the cowl was scuffed slightly as though a blade had been catching. Could a fan be 'out of balance', and like putting lead weights round a wheel, this be a way of balancing it?

Thoughts appreciated, thanks.

[TwinKam]

Was quite common once to see metal balancing clips on fan blades, not much now prob due to more accurate moulding.
Run it up to speed with and without and see if there's a noticeable difference.