Board needs to be very clean, no flux residue. Make sure C7-C9 and C14 are facing the right direction. You can check the LFO alone by doing this: Temporarily connect a superbright LED cathode to ground. Temporarily connect a 22K resistor from SPEED pot pin 2 (either pin 2, doesn't matter which) to LED anode. Set SPEED to the middle. Does the LED flicker? If it does, the LFO is running. The LED will flicker more brightly at high speed, and the flicker will be weak at the lowest speed, that's normal for this LFO.
I have a Photon Vibe mod in progress (almost done) and I can tell you that the LFO is very touchy. If C7-C9 are leaky or the wrong values, the LFO won't run.
jpalmer, you probably should have started a new thread since most of what's in here (like the pix and measurements) do not apply to your build. Post pix of your board, let us know if you subb'ed ANY parts.