A week later and still struggling to do simple things like putting a shirt on because the movements required induce pain in my shoulder. Not where the x-ray or bruising suggests the trauma is located. However paracetamol every 6 hours is containing things if I behave myself and don't exert myself. Couldn't resist looking at the semi-stripped motor in the workshop so persuaded Mrs J to take me to George Lodges with the old bearing I had taken off prior to my fall. The lad behind the counter measured it and said it's a 6204 2Z stock item do you want a pair? Price £71.51 plus vat

then said discount 92%

so I bought two and came away £13.73 lighter. Thank goodness for discounts.
It'll probably be a few more days before I'm up to fitting the bearings and the end caps go back on the motor.
While I was there I noted they stock a wide range of pulleys and belts so if I have future requirements there's a local stockists.