Blackforest shelf clock (Canadian made) gives me grief but decides to run again

Blackforest shelf clock
Blackforest shelf clock

The clock is a 1937 Blackforest Royal Tour commemorative edition shelf clock with an 8-day time-only “plate” clock movement. Plate clock movements are so-called because they were typically used on kitchen clocks with Dutch Delft plates such as this one in the next photo.

Delft Clock from Forestville
Delft Plate Clock from Forestville

The movement is likely German and could have been made by a number of companies. There are no stamps or markings on the movement to give any indication of the maker. Canadian companies such as the Blackforest Clock Company of Toronto (the Forestville Clock Company after the war) imported German movements before the Second World War and installed them in Canadian made cases.

Grimy movement prior to cleaning
Grimy movement prior to cleaning

This clock had been happily running for about a year and then last week it suddenly stopped after a winding. I nudged the pendulum in an effort to make it go, checked to see if it was in beat and level but no luck. I nudged the pendulum a few more times, left it for a day or so, tried it again and still no luck. I was at the point of disassembling the movement to investigate the problem. Two days later I wound it tight and gave the pendulum a push and it sprang to life. I think I know what happened.

I thought I did a good job of servicing the movement including the mainspring over a year ago but apparently not well enough. You may have heard the expression, “you overwound the clock so that’s why it stopped”. There is a grain of truth in the expression because if you wind the spring till it winds no further the mainspring is at it tightest. If there are dirt, grime and rust on the mainspring the mainspring will actually cease in place, hence the clock stops. I believe this is what occurred in this case. Although it is running now it will need to be properly cleaned. In the meantime, I will let it run and see if it completes its full 8-day cycle.