Hi and welcome t Just answer.
Please follow this step on how to remove your bobbin winder assembly.
Next, WITH CARE , lever round the tray with a thin blade and use a small screwdriver to ease it out of the case; there are 2 bits that stick out more than the rest.
TAKE CARE NOT TO DROP THE SCREW INTO THE WORKS!. A piece of sticky-tack on the end of the screwdriver helps here if the screwdriver is not magnetized.
The bobbin winder mechanism is held in by 1 screw - take this out and you can then easily replace the rubber drive ring -(which you have providently ordered)
I took both my CS 8080s apart last week to replace the drive rubbers. The first took nearly 1.5 hours, the next 1 hour as I knew what I was about.
Hope this information will be helpful.
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