Self and son took it apart, greased it, put it back together, it works.
A slightly squished breech seal was noticed (pictured), a couple of tiny balls of weld spatter and tiny metal flakes were extracted from the compression tube (?), and the somewhat rough end of the mainspring guide (pictured) (?) was remarked on.
The old grease had become very sticky and in places seemed to have formed a tough rubbery coating (pictured) devoid of lubricating properties.
The trigger housing block was quite tight. A piece of brass flat bar just smaller than the slot was inserted, and knocked around to unscrew using a timber batten as a mallet. There was a considerable preload on the mainspring, which was held back with a screwdriver while the block was unscrewed. When the mainspring was released, it was caught on another strategically and tightly held wood block, on which it left an imprint (pictured)!
Screwing the trigger block back in was a difficulty. To overcome this, a tool was made from 7 1/2" (190mm) long piece of 42mm diameter plastic waste pipe. The trigger housing block was put, threads up, on a flat surface, and the pipe placed over it; the end of a 3" (75mm) galvanised nail was heated and used to "drill" through the pipe, then following a secant through one of the pin holes in the trigger block, right through the other side of the pipe, leaving two holes (pictured).
The pipe containing the trigger block was then slid down over the vertically barrel-down assembled action, and the whole lot carefully inverted and placed with the end of the trigger block on the floor. The pipe was held, then the action pressed down carefully and rotated, keeping the whole assembly vertical, around a vertical axis, to engage a few threads, before being lifted and the screwing-on completed. Lastly the nail and pipe were removed, and final tightening done using the piece of brass flat bar used in the unscrewing process.
