When this movement came in for repair it had extremely strong replacement mainsprings from Germany (the ones that uncoil to over 20″ diameter when released). I don’t like such strong springs in American clock movements, especially the Seth Thomas 89 movements, which are efficient).
After routine repair (pivot polishing, bushing) and not so routine repair (having a new ratchet wheel made), I installed two new mainsprings – the Merritt’s Antiques P-1496 in Red/Yellow package. The thickness is 0.0165 inch. The video below shows the escapement motion and pendulum motion with the time mainspring 10 1/2 turns run down and fully wound. This mainspring provides enough power, yet not too much, for this clock movement.
Job 5077.
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