Electro-Harmonix PolyChorus Help

[malibuclc]

Just joined and not sure if this is the right place but I'm sure someone will let me know.  So I just got a 1980 E-H PolyChorus and have a problem.  The pedal was functioning properly for a couple days and then while using it there was some noticeable static through the amp for 5-10 seconds and then a loud pop.  There was no smoke or burning smell from the pedal.  Now the pedal still functions 100% properly but the effect is much weaker (about half as intense).  I opened it up and could not see any burned components or problems but I have no experience with electronics/pedal repair.  I have no idea what I'm looking at - transistors/capacitors I couldn't tell you the difference - they're just red and green things.  There is some sticky black stuff under one of the parts, don't know if thats significant or not.  But I would think it would be something simple and have some common sense, so I would like some direction on what I would need to find the problem (simple voltmeter, schematics,) and how to to test different components to find the weak link.  Also, I don't know if this could be connected to the problem, but there is a blend switch on the PolyChorus and when switching between blend and off there was always some static and it gave me problems when trying to switch back to full effect (would stay blended).  So I left the blend switch alone when I got it back to full effect (was not touching this or anything else when I heard the pop).