Yes, but what I read is that developing time is generally minutes and exposure is in seconds, and all "darkroom" timers I've seen are graduated in seconds with a minute hand. I'm pretty sure the hand did not just break off as the circumference is fully painted and smooth, and also that there is no internal lever to reset the minute wheel...
With 100 units to the minute, it's not too easy to figure out where 17 seconds is, for example.
Calibration? Yes, I popped the hood and there is what I think is called a regulator thingamajig. I have one of those regulator apps on my phone too, I think called a timegrapher.
Operation is simple. The left lever has run and stop positions. The right lever is spring loaded and resets the 0.6 second hand only.
I was half tempted to glue on a minute hand until I realized the minute wheel is not reset. I'd have to figure out that part of the mechanism.