Is it safe for me to test my trigger safety mechanism by pulling the trigger when the safety knob is in the “S” (SAFE) position?

No.  Your crossbow is a deadly weapon designed for target shooting and hunting.  The only safe approach to using a trigger is to assume that whenever you place your finger on it, it will fire.  Do not place your finger on the trigger unless you are ready to take a shot.  Moreover, you should never disengage the trigger-safety, moving it to the “F” (FIRE) position, until you are ready to take a shot. 

If you have any reason to suspect that your trigger mechanism is not functioning properly, discontinue use of your crossbow and call our Customer Experience Team at 330-628-9245 (M-F, 9 am to 5 pm, ET) for further assistance.