I am basing my suggestion on the 2 riders that I owned. The brake disc is driven by the transmission (or transaxle) There is a brake pad that rubs against it. This was the case on my 11 hp Murray. I now have a Snapper 16 hp hydrostat drive that has a round cup-like disc driven by the gear box (reduction gears driven by hydrostat). There is a brake band that wraps around this disc. Brake is activated by clutch/brake pedal cable. The cable end that goes to the brake has thick washer-like rings on the cable. You slide one or more of these over the end where the cable attaches to brake band to increase tension. Maybe someone else can help you better than I. You will just need to learn how it works--it gets quite frustrating at times--Good luck
Robert Brown
September 2008