New battery, slideout won't work

Went camping over the weekend. Lights and slideout all worked but the electric jack quit working. Used my manual crank and figured I would get a new battery upon returning home. the old one was dated 2008, so it had outlived it's expectancy.

Well, I get home and now the slidout wont fully extend either. Almost, but no cigar. No biggie, I knew it was likely the battery so I put the jumper cables on the camper battery and the jack instantly worked. Didn’t even bother to check the slide out because I assumed from the jack suddenly working, that it was a battery problem. Hop in the truck, run to Walmart, get a brand new (July/2014) Deep Cycle 690 CCA battery and head back to the camper.

I get to the camper and hook up the new battery only to find that now the slide out won’t even make it half way out. Worse than before with the old 2008 battery. I check the jack to see if it’s getting juice and NO PROBLEM…jack works fine. Lights work fine as well. The slide out…not so much.

So, I assume the new battery must be weak but am perplexed because when we were camping, the slide out worked but not the jack, so you would think the jack takes more juice to operate…but now…the jack works and the slide out doesn’t. In fact, the slide out barely moves before giving out now. It does try, but doesn’t make it far.

So, just in case, I let the battery charge overnight through the camper charging system. Get up this morning, check the slide out…same results!

I have checked the slide out for any obstructions inside the camper and underneath. There is nothing binding or preventing the moving parts from moving. The camper is level.

I have one last theory to test, and that is:
I parked the camper further away from the house to give the grass a break. Because of this, I had to use my 25’ extension cord (first time ever on an extension cord). I verified that it’s getting juice and the breaker is on. The cord is rated adequately and I remember it cost an arm and a leg. However, my theory is that the extra length of cord is creating a degradation and unable to supply enough power for the slide out. This doesn’t make sense to me because I thought everything ran off the battery…but it’s the only theory I have left that I haven’t tested. I suppose, the new battery could have been strong enough to power the jack, but too weak to run the slide out because it came depleted off the shelf and the charging system in the camper has taken a******and not properly charging??? It’s a long shot but that’s all I got.

Keystone Cougar 294RLS
Nothing binding the slideout

HELP