There is no clockwork mechanism in the ST901. Clockwork mechanisms are for timing a fully open shutter. The higher speeds are achieved by narrowing the distance between the shutter curtains as they traverse.
The ST901 has essentially the same mechanical shutter mechanism as the ST701 and ST801 manual exposure cameras, but does not have their clockwork mechanism to time speeds slower than 1/60, so it has no manually selectable speeds slower than that except B, nor does it have any speeds which are manually selectable and electronically timed. The manual speeds it has are mechanical and fully independent of battery power.
Sorry, I missed this edit before. You should be OK to desolder and resolder any wires. The wires in the Fujica ST801 (and maybe 701) had Teflon insulation, and should be good. I would expect the 901 to be the same for any wires it might have. I have not been into the ST901 or other Fujicas. I don't know the details of how the curtain distance is established.
Originally Posted by Eugen Mezei