Hotpoint WD71 - has the bearing gone?

On Christmas Eve (typical!) I went to get my washing out and was faced with a room full of stinking smoke.

I looks like the drum had somehow got stuck and the motor spindle slipped on the belt. The belt was intact but noticeably thinner at one point so - although when I open it up the drum was moving freely. I've replaced the belt and there is now no smoke.

However, while testing it on a 1200 spin as the drum speeds up it makes a loud roaring sound which goes more a like a whirring noise once it hits top speed.

Everything appears to be running smoothly apart from the noise, but there must be something wrong somewhere. I still can't understand how the band got 'worn' in the first place, so I'm sure I've treated the symptom but not the cause.

Grateful for any help anyone can offer.