I’ve got it fairly accurate now (approx 30secs/day) but suspect the movement will drift.
(Picture says 25s/day but it drifts around).
Anyway much cheaper than a quartz movement or new clock, and keeps the original.
For those who want to try it:
You’ll need a TGBC timegrapher from AliExpress (or £16.49 from Amazon)
First calibrate with a quartz movement ‘moving hands’ clock
Importantly, Kienzle clocks run at 16200 beats per hour, so you have to over-write the bph display with this figure
Keep sample rate at 44.1KHz and lift angle at 52 degrees.
Clockwise slows the clock. CCW speeds it.
I’ve not measured how far to turn the adjusted for each 60 seconds/day change, but feels like about 20 degrees. Make small adjustments each time and stick a cocktail stick onto your watchmaker screwdriver so you can see how far you turned each time.
Wait 10 minutes after each adjustment for the movement to settle.
Oh btw I’ve read in some chats about removing the clock by dremeling the straps (on later cars that don’t have U clamps). Don’t do that! The clock just pushes out from the back.
Hope all that helps someone.