Bluesbreaker pedal with cap switch cuts out

[spargo]

I have built a modified clone of a bluesbreaker.  I've added a SPDT switch to the circuit.  It switches between two capacitors for different EQ, both of which are grounded.  The other pole of the switch turns on an LED when in one of the positions.

This *was* working great for a few hours, but now it's started cutting out (works 100% fine in bypass).  I believe I've isolated the problem somewhat - the cutting out (signal dying mostly or completely) happens only when the switch is in one of the two positions.  One of the positions always works.  Everything seems to be connected correctly, and both capacitors are grounded fine according to the multimeter.

Any ideas what may be causing this?

Also, I'm still getting a pop when switching the pedal on/off with the true bypass.  I thought the schematic already included a 1M5 pulldown resistor, but am I mistaken?

[spargo]

And if it helps, I measured the voltages of the IC chip.

When the switch is in one position (pins 1-8):
4.25
4.25
4
0
8.5
4.25
4.25
4.25

When the switch is in the other position (pins 1-8):
4.65
4.25
4
0
8.5
4.25
4.25
4.25

And when each cap is selected, they are both showing 4.25 volts.