I camped with some folks with a electric lift-equipped Starcraft popup last year, and I know it had a manual crank since they used it when the battery went dead. Don't know if it was the same model, but similar vintage and this part is the same for all according to what I understand. The handle looks like the one below, which image also shows the size of the opening you're looking for.
It's a little hazy in my mind, but I THINK that the "socket" you're looking for is sorta hidden behind a cover right near the on/off switch. And it might be coated in grease which would further camouflage it.
Image source
