So, the trimpot was indeed the culprit. It’s 1K instead of 100K. Got me one with the right value from a nearby store. It’s a little bigger, so it doesn’t fit, but I soldered some wire to it and taped it to prevent shorts, connected it and lo and behold: a beautiful chorus effect came through my amp!
So I guess this was an honest mistake by Klaus of Musikding. Will be mailing him.
Thanks for all the help guys!
Here’s a picture (it’s very pretty, I know..). Cheers!