Grinding noise when my F&P ECS starts filling ?

We have an old (20 years plus) F&P ECS washing machine model RW52. It's been working fine with no problems until today.
We switched it on, set it to spin, put in the clothes we needed to be spun, and then started it. It starts ok but makes a "graunching" noise while the paddle/drum moves. I guess it could be a bearing, or is it possible that there's something like a button or similar stuck somewhere within that paddle mechanism?
I've removed the back of the washer, the drive belt is fine, and both drum and paddle can be moved ok by hand.