Hi Rob,
My goodness, I thought I was gonna lose it!
I was 100% sure, that I've already already seen the wiring diagram of the rotary encoder in the eDRUMin manual.
Yesterday, the soldering iron was heated up. All the parts ready ... and ...
https://www.audiofront.net/eDRUMin_2.3.pdf ... no diagram. Huh?!
I just soldered it together from memory and it worked fine.
Now, I NEED to double check it and found it via Google in
https://www.audiofront.net/eDRUMin.pdf