If your still in the market contact Bruce Pitt on 082 333 5891. He is selling his, excellent condition. I think its a 1980 block inlay model

The fact that it works as a volume pedal when turned on indicates that power supply, connections and switches are all ok. The circuit is in fact working, but the variable filter section tuned mainly by the inductor and capacitor I mentioned in my earlier post is not - most likely a faulty component, or poor PCB connection on one of these two components. In fact it is a known Wah to Volume pedal mod to disconnect the 4.7uF cap from ground.

It is not difficult to repair, and any decent CT-based repair shop should be able to diagnose and fix fairly quickly - no need for a new pedal. If the inductor is kaput, there are plenty of aftermarket replacements available for around $25, but not sure if available locally so you might need to purchase online from the USA. Google "Fasel Inductor" for more info. Circuit diagrams for wah's also freely available on the web.

Check out this excellent article from RG Keen for all the info you ever needed about a wah pedal - http://www.geofex.com/article_folders/wahpedl/wahped.htm

hope this helps

Most likely the capacitor (normally around 4.7uF) in series with the inductor that is faulty, or the inductor itself. Could be open circuit, or even a bad connection to the PCB.