In need of New Holland Round baler expert.

I have an older NH 644 silage special. Recently the bale size adjuster does not work like it shouldid and the bale size varies depending on the thickness of crop, moisture excetra. It still beeps when it starts the tie cycle which is usually a full bale at the stop arrow. Is their anyone here that can give me some advice or should I just get a big hammer and beat on it until it works?

In need of New Holland Round baler expert.