Using a 1-3/4" socket, and a piece of wood between a crankshaft web and the engine block, managed to get the starter bolt undone, and after that it wasn't long to get the timing cover off.
Below: the cover off, revealing the timing mechanism. Old gaskets were made of cork (as on the sump).
Closer look at the timing chain and related mechanisms. Can you spot the problem?
Here's the problem: the chain adjustment cylinder casting had broken at some point, and the ratchet catch had fallen from there into the sump. The ratchet arm, judging by the wear on the remains of the casting, had been sitting directly on the casting for some time. However, as the casting pieces had broken clean away and left a gap, the ratchet itself appears to have perhaps continued to work, in a way, but now by catching the side of the hole. This is visible in the photo above. The chain does not appear to have made contact with the engine block, judging by the undisturbed dirt and lack of scarring.
The chain damper looks a little beaten up, and so have ordered not just a new cylinder for the adjustment ratchet, but a damper as well.
