Very noisy ideal classic lxff ff60 ?

Hi,

Our boiler makes an awful grinding/whirring noise that can be heard outside the house and inside. Is there a problem with the fan?

When it's running the noise varies in intensity, sometimes it calms down and is mercifully quiet, the next time it fires up it will be very loud again.

Please see the video: https://www.youtube.com/watch?v=Qy6I-OgTGMw