The main pivot, the hollow large one on the rocker arm seems a bit loose, its a new bike that came by mail order. I can see that there is from one side a place to put a large alen key, and the other side is just a circular tube, there is a small alen bolt that can clamp the rocker on to the circular side. I can feel a bit of play there, any idea how to tighten sort the problem please ? many thanks ..

Got a Cube Fritzz which uses the same design – which is essentially a threaded two piece hollow axle. And it does have a tendency to work loose…

I removed mine and thread locked both the axle and the pinch bolt threads. Slacken the (small)3mm pinch bolt and then the axle (10mm) Remove the two pice bolt and apply some thread lock to both this and the pinch bolt. Re assemble axle first then pinch bolt. Make sure you dont get thread lock on anything else. The pinch bolt does need to be nipped up pretty tight but be careful you don’t strip it. The axle should rotate with the rocker – if it’s loose the rocker rotates around the axle. Not good…

Thank’s for that very detailed answer, have a great weekend, and thank’s for taking the time to help me out… 😀