Power tongue jack weak battery

I've got an Atwood power jack on my tongue. It's hooked into the rv battery of course. Lately, when I'm hooking up at home for a trip, it seems as if the jack is very sluggish even though I know the rv battery itself is fully charged. I keep the rv plugged in full time at home. When I back up the truck and plug the rv into the truck battery connection the power jack works fine.

So is the problem likely with the connection from the jack to the rv battery? Not with the tongue jack motor itself, which does seem to work fine when connected to the truck and running off the truck battery? I just want suggestions where to start looking first for the culprit.

Thx.