Thanks, both of you
Finally was able to open that clip, probably would've ripped it apart if it hadn't been for your help.
Managed to wriggle the actuator out and establish the problem: the cable had come unhooked on the actuator side. Don't know how, it looks fairly impossible to me...
Anyway, that's now sorted. Are there by any chance any tricks to put the actuator back in or is it really just wiggle and fiddle until it's back in?