The brass dial (with T, B, I) on it should turn, rather than just the arrow?
Watch:
https://www.youtube.com/watch?v=rHXWF2k5XG8Note he starts with dial on "T". Press lever once, it opens. Press again, it closes.
Next he turns the dial to "B". Press, and the shutter remains open while finger is on lever.
Finally he turns the dial to "I". Select time. Press lever once and shutter opens for one second. Turn dial to 2 (which is 1/2s), press lever and shutter stays open for 1/2s, etc.
Kent in SD