your S2 may be working fine, but it's a good idea to test it because 1.) it dates to 1965 and 2.) the S2 initially had a lot of problems with jamming that were corrected with the S2A. The S2 didn't have a good reputation. I don't know if there were upgrades available for the S2 or not. If there was, yours may have had them installed.
Flash sync was very slow, but the Nikkor lenses are superb. There was also a 50mm Nikkor wide angle. After the S2 and S2A, there was the EC with electronically timed shutter, and after that, the ECTL with TTL metering. (then Bronica went to the ETR with leaf shutter.) The backs for the S2, S2A were not compatible with the EC and ECTL, but the lenses were. I had an EC "back in the day" and liked it, but repairs were pricey (it was complicated) and it was difficult to find an independent shop that would work on it.