Multi-effect popping woes

[skrunk]

Recently finished my first attempt at a multi-effect with a TS808, NPN rangemaser and Mosfet boost circuits.
I built it on 2 boards, one for the TS and one for the 'boost section' (the RM and the mosfet boost).
which boost is active is selected by a toggle switch.

the TS and boost section each have their own footswitch and can be turned on/off independently.
there's also an order switcher toggle to select the order of the TS and boost section.

everything works fine except for some popping trouble I'm having when each effect is engaged with the footswitch.
I've been reading all the popping threads and here's what I've tried so far:

I've disconnected the on/off LEDs (there's one for each section) and the popping remains.
There's a 1M pulldown on the TS board, a 1M pulldown on the mosfet boost circuit and none on the RM circuit, which has an input cap blend control.

I measured the voltage at the negative end of the 10uf electro at the output of the TS (to check for leaky cap) and it was 0v.
I tried putting a 100k to ground at the output cap of the RM and mosfet circuits (using test leads attached to the footswitch) with no luck there either.

I also get a pop when switching the 'boost select' DPDT toggle, when going from RM to mosfet boost and vice versa.
This isn't so much of a problem as I can select what boost I want to use before I engage the footswitch, and it goes away after flicking back and forth a few times.

Engaging the TS seems to be the worst offender. Engaging the boost section pops also, but it goes away after a few stomps but the TS popping remains even after a few stomps.
I've built these circuit on their own without any popping issues, so I'm guessing it has something to do with my layout or wiring/switching setup.

Any thoughts on dealing with popping with an effect like this?

[skrunk]

not sure why that image is coming up so small??