The Horolovar 400 Day Clock Repair Guide specifies a 0.0023 inch thick suspension spring for the Schatz model 53 miniature movement. I just repaired one that ran too slow with a 0.0023 inch spring, so I installed a 0.0024 and it keeps good time (my repair job no. 5212). The pendulum looks normal, but perhaps its weight is slightly different?
I repaired another one a couple of months ago (job 5113) that also needed a 0.0024 inch thick spring. This one was slightly different in that the spring needed to be 1/8 inch longer than usual for the pendulum locking device to work.