Kegga62

A few day's ago. I noticed that my volume/wah peddal on my FVB MkII Shortboard was loosing it's resistance. While playing and trying to control volume. The pedal drops to full volume. I use a rag under the pedal to try and keep it from dropping to full volume. I haven't tryed fixing it yet. I wanted to check here first and hopefully find a way to fix it or if there is a part I can buy to fix it. Any help would be great.