Maestro Octave Box short/choppy octave Tone

[Drewmeyer]

So I bought a Maestro OB-1 off eBay recently and ,as described by the seller, it does not seem to work properly. The lower octave notes play for only a very short time before they cut out. As well, the octave note is inconsistent and will only sound if any previous note has been muted entirely, making playing quick passages of any kind impossible. Information on this pedal is pretty scarce, but on a few of the sources I've found I've read of similar problems, so this seems like a standard thing. None of the parts inside look physical damages, but I suppose it's possible some of the parts could have gone bad since it's a rather old pedal. The schematic can be found here: http://www.guitare-village.com/occasion/_images/2011/20111226/maestrod2.jpgAny idea what (if anything) could be the problem and any tips on how I should go about troubleshooting it? I can post pictures of any necessary area of the pedal if their needed.