Boss Metalzone problem

[Crawf]

Hi,I was wondering if anybody had any thoughts on this, I recently bought a Metalzone from E-bay for a decent price and having experience of one a few years ago i thought i would do some mods to it which are freely available, i bought the Monte Allums Sustainiac mod sheet from his site and proceeded to carry out the mods to the pedal, when i had completed the mods everything was working ok and the pedal sounded good but when i turned the "Low" control past the 3 o`clock position the volume was cut. Now i must admit i never checked it before the mods so what i`m wondering is could modifications involving capacitor changes and some diode changes make the pot do this or could the the pot be faulty, sorry for the long winded explanation,hope someone can help although its not life or death, i can probaly live with it if it cant be fixed, thanks Crawf.