OK, I've tangled with many cuckoo clocks and have a pretty solid understanding but this one has me stumped. The top mounted music box functions fine if drum is given the opportunity to advance a smidge so the pin doesn't return to the hole. But, under normal operation the pin lifts from the hole and the warning wire stops the fly so the drum can not advance ( or music play) until the cuckoo is done sounding. When the cuckoo is finished the wire moves from the fly and at the same time the pin/lever/arm assembly is released....the pin falls back into the hole and the arrester lever/arm stops the fly. IOW, the drum has no opportunity to advance clearing the pin from the hole. The pin/lever/arm assembly does not have an elongated hole slot for lateral action like most, just a round hole. What idiotic mistake am I making?