On mine, the cable was kinked where it was connected to the hatch. I straightened it out, then discovered I had to lubricate the cable because it was sticking badly.
I shot an aerosol of silicon spray into both ends, IIRC, then re-adjusted its length so that it closed fully, using the fastener (nut and bolt) which is behind the Master Control Panel on my '74 Sov.
I don't think that the Argosy units had the "Master Control Panel" (guages and stuff) but that is where the fan and door is activated on my trailer. A slider opens the hatch and at the end of its travel it turns on the fan.
The fan works, but is low power and high decibel output and so is rarely used.
If it's to be, it's up to me.