my baler is a 664, i think basically a very similar baler but a year older. on the 664 of mine. the alarm will sound when the bale has reached the size i want, then again when the bale is finished tieing. if the alarm systems are the same....look under the baler in the front on the right side.(the balers right side) there should be a micro switch(not sure if thats what it is called) but its a small black switch with a short thin spring and a small swivel on the end. when the baler is making a bale that swivel should be seated in a slot with little or no tention on it . when your baler is parked run it through a tie cycle and watch that swivel and make sure it starts and stops in that slot. if not there small screws you can loosen and adjust . if the 688 and the 664 have different tying methods, i guess i just wasted your time by reading this. good luck
I have a 688 New Holland round baler with auto wrap. Just got it a couple of weeks ago. When I first got it the alarm would sound for the auto wrap when it first started to tie. Then it went from that to sounding the alarm when the bale got done tieing. (not when it started but when it was done tieing). Now it sounds the alarm from beginning to the time it is done tieing. How should the alarm work and when should it sound. It does not say anything in my owners manual on how to adjust this or when it is supposed to sound. Can you please tell me how to adjust this and how it should be working. Thanks Gil