With some final sub-5 degree adjustments to the balance wheel tensioner
, for one thermal time of year , could probably get it to 5 seconds per
day accuracy. What with the 1/6 of one turn of the mainspring used only
and independent of battery state of charge. I reckon as 40mA of current
use one second per minute then with a 4Ah D cell the clock would run for
9 years. The replacement plastic cog is fibre reinforced so perhaps that
one will last another 40 years.
Even the alarm works. Would originally there have been active
flourescent or radioactive numerals? no sign of any "Glo" with no room
light, only illumination is if you switch on the internal lamp.
Just had summertime clocks change here, could not be easier to adjust
this clock, just turn the small knob on the side 6 turns forward or back.