An agricultural baler (10) includes a main bale chamber (26), needles (36), knotters (34), a triggering system (52), a knotter lock (54), a blow-off mechanism (56) and a monitoring system (58). The needles (36) are coupled to the main bale chamber (26), and thread twine around a formed bale. The knotters (34) receive the twine from the needles (36) and tie the twine. The triggering system (52) activating the needles (36) and the knotters (34). The knotter lock (54) is a manual lock of the triggering system (52) thereby preventing the needles (36) and the knotters (34) from being triggered. The blow-off mechanism (56) directs a flow of air at the knotters (34) and the needles (36). The monitoring system (58) has a single sensor (76) that provides signals indicating a normal operation of the knotters (34), an engagement of the knotter lock (54); and a time to trigger the blow-off mechanism (56) for a predetermined amount of time.