A friend has a new-to-her Leclerc Nilus 45" loom with a double warp beam.  The friction brake on the second warp beam is operated by the weaver by pulling a cord. The problem is that nothing happens when I pull that cord and I cannot find anything obviously wrong when I look at the brake assembly and compare it to the manual  https://www.camillavalleyfarm.com/manuals/Other/DoubleWarpBeam/DoubleWarpBeam.pdf (but my mechanical abilities are limited). Does anyone have experience with this loom wiht two warp beams ?  
Thanks
Isabelle