Need some help with an Ibanez PH-10 Bi-mode Phaser.

[Beaker]

I've just rescued an old Ibanez PH-10 phaser from pedal Valhalla.

My son was given it for free, as the footswitch was smashed, and the 6/10 phase toggle switch was missing.

I found a schematic, and a page with some details on this pedal on Mirosol's blog, so I was able to easily fit a new toggle switch.

What's left of the footswitch has only two leads, and when I cut and stripped the wires to see what was going on with it, found that it seemed to operate with a "double tap". In other words you need to make-and-break the circuit to turn on, then make-and-break to turn off.

I have hooked up a SPST momentary switch to it, thinking that would do the job. A single press on the switch seems to turn it off every time, but not turn it on every time - it sometimes needs pressing a couple of times.

Am I missing something here - is this switch not suitable, or could it be something else?
Looking at the schem, I'm wondering if it could be a cap charge/discharge issue. I'm looking at caps C35, C36 and C37 and wondering if the issue could be with one of those?

I'm really not familiar with this type of switching, so any help would be appreciated.

Here's the schematic:



Here's the link, so you can see it full size:

http://8bitsindgenug.net/ibanez_ph10.png

Here's the link to Miro's blog page:

http://mirosol.kapsi.fi/2014/02/ibanez-ph10-bi-mode-phaser/

I really want to get this working, and re-housed as it is a cracker - it absolutely nails Smashing Pumkins' "Rhinoceros".