It's probably just circuit noise in the empeg. But perhaps you have a fast enough scope to take a similar sample there?

This was just a Mk2a, with latest Hijack, plugged into (60Hz) mains. Test probe on pin-1 of the sensor chip, which is hidden underneath the display ribbon cable.

I'm thinking that we only see the noise because the scope samples at 1 gs/sec. A slow scope might miss most of those glitches. Does that make any sense?

Cheers