Probably the infamous fuse #2. When you turn on the key, look to see if the
PTO light is illuminated on the instrument panel. It does not matter where the
PTO lever is. When fuse #2 blows, the
PTO light comes on no matter where the lever is.
Replace fuse #2 with a 10 amp fuse or an 8 amp self-resetting circuit breaker. The standard fuse they put in that circuit is 7.5 amps and that's too small. It will blow from time to time. Your battery is probably a little weaker than normal because it sat for a long time. That small amount contributes to this problem. With the larger fuse or CB, you avoid this problem most of the time.
BTW: The fuse panel is under the instrument panel. Remove the two screws on the panel and gently lift it out of the dash. Wipe the dust off the fuses on the left side under the panel and pull the 2nd one from the left. That's fuse #2.
If you want the self-resetting CB, you can order part number 86610928 from your NH dealer. You should also be able to get one from CarQuest as reported by RickB who is a NH technician.