Following the instructions on the Retina Rescue site - and thank goodness for finding them, dismantling and reassembling the flash timer is a right laugh! To anyone who does it, follow his instructions to the letter.
The amount of dirt that has come out is incredible. This is the third Compur shutter I've worked on and they've all been filthy compared to Prontor or Copal. It's back together and the non-latching main lever should be sorted, so getting there.
How does this thing work?