Here is a manual for JAK. Not the best of wording or understandability, IMO. But that's common for the small budget manufactures. There is useful information in it. Such as what measurement the pads need replacing by. https://classic-cycle.de/media/pdf/M...AcWKmlQZW2FPpF

Also, here is a Youtube video about them. No speaking, but it does show some key things if you dwell on it a little and have some DIY ability and mechanical inclination. You can look for other YouTube videos that might have verbal commentary to explain more.


You also need to see if there is a barrel adjuster on your shift lever for the cable. As well, the one on the brake body looks all the way in, so maybe too slack a cable that doesn't pull enough. I don't remember if you ever said what condition the brake pads are. They should be checked to see that there is enough pad material on them. If the legs of the retainer spring are the same thickness as the pad next to them, then it's well beyond time to change the pads.