After looking at the layout and looking at a revised schematic that Casper Electronics posted:
There a few subtle changes.
- C1 has been assigned a value of 47uF instead of 100uF ( Im sure this really does not matter since its just power filtering)
- R19 has been removed. This is a 4k7 resistor off of pin 3 of the TL072
- The 330k resistor at pin 5 of the op amp has been removed.
- Feedback pot needs legs 2 & 3 swapped.
