Small Stone not phasing?

[Jazznoise]

So one of my lecturer's has offered my a Small Stone for 40 euros, which isn't bad going! But it seems to have issues that the LFO speeds seem to have collected around the Clockwise position of the knob, and it simply stops phasing after 12 o clock. It also only seems to show any phasing with the colour switch down.

Looking at the schematic I'm wondering if the issue is the Vref? I'm currently powering it via battery as the DC connector is so damn weird.

Jumping the gun abit, but it's on the premise of my purchase so I was also wondering if anyone had tried adding mods like variable feedback or an expression pedal input for the speed?

Any help is appreciated!