If brake is not moving: The first thing you'll want to find out is what type of brake you have: friction brake or gear brake. Harrisville Designs switched to the friction brake in 1980. 1. Try cleaning the groove with a file. 2. If the cables are old, the rubber could have degraded and gummed up. We suggest buying a new brake cable. 3. Your tension could be too tight, especially with a less elastic fiber like cotton. You'll need to put the warp under greater tension to achieve a good shed, but a friction brake will not work under too much tension. Try weaving with looser tension to see if the brake function improves. 4. Sometimes the brake is working but the beam and drum have separated. a. To diagnose, using a pencil, draw a line that extends onto the wooden brake drum and warp beam. b. Engage the brake and turn the warp beam. c. If the pencil line does not stay together, it's likely the pins holding the beam and brake drum together have sheared off. The warp beam must be replaced at that point. 5. Check that the spring is hooked correctly to the bell crank or brake bar. If not, be sure it hooks from the inside to the outside. If the brake/beam is slipping: 1. The brake may have been installed incorrectly. You'll need to determine whether you have a hand or foot brake. a. Brake bar or bell crank should run parallel to the floor. b. Can make minor adjustments with the wingnut i. Should test it with each couple of turns. c. Nylon brake cord should run inside of the spring d. Can also adjust with the chain 2. The disc maybe too smooth and cause the cable to slip a. Could try to rough the disc with a file 3. The cable should not be crossed in any way 4. The coil is old and lost power and should be replaced 5. Some people choose to glue sandpaper in the groove. This will wear down your brake cable over time. Also, sandpaper will wear down quickly