If there is no electric motor or a hydraulic cylinder like the one in the picture, you probably have an auto-wrap baler.
They are mechanical and fully automatic. All you gotta do is stop the tractor and dump the bale when the tie is done. However, ya need that warning buzz box to let you know when things are happening so that you can stop the forward travel.
Are your arms located/mounted in the center of the baler or are they hung out by the sidewalls?
The mechanical tie style will wrap from the center out and use a knife mounted at each outside edge to cut the twine.
Hydraulic and Bale Command units tie from the outside in towards the center of the bale and use a "hammer block" mechanical unit affair to cut the twine in the center of the machine.
If you have an "auto wrap", all you're gonna see under that left cover is a bunch of gears. No electric motor and no hydraulic cylinder.