Fixed

What it needed was just a bit more dismantling than I'd dared yesterday. Turns out there's a separate little mechanism that deals with slow shutter speeds and is notorious for getting gummed up with old oil over time. Take it out, wash it in Isopropyl alcohol and it's as good as new. There's no shortage of very dull instructional videos on YouTube. 

I don't know how accurate it is. Could be 1 second, could be 1 but it doesn't make too much difference. Film wants to be over-exposed a bit. With the right developer, black and white can take a lot of punishment.

Apart from that I frittered the day away on the first loaf from a new sourdough starter. I think I might have rushed it. It's not as awful as my first first sourdough but it's not the majestic ball of dough you might hope for.