Here is a current photo of the rubber ring, I am using now, which turns the rotate knob also into a jog wheel. I’ve been working like this for a long time now and it’s the best choice for me. There are several sellers on eBay who offer such a model.
You just have to make sure that the inner diameter of the ring is approx. 18 mm. The rotate knob has a diameter of 20 mm, which means, that the ring is stretched a little, when you put it on. This ensures, that the ring sits firmly on the rotate knob.
