Charger stops charging after around 30 minutes

[flipture]

(I've seen the other threads similar to this one but I was unable to find a resolution from it)

So I'm pretty new to carts but have been reading for two days and have already done quite a bit to troubleshoot and fix this issue before posting... I got this cart off of a trade. The cart was said to be in good working condition with 2 year old batteries. When the cart was dropped off, it would barely make it up my hill during the test drive and the previous owner said that it just needed a charge... Not sure if I should have believed this or not.

I put it on the charger, came back later and the charger was not charging any longer. The cart would still barely make it up the hill and very quickly (within a minute) would barely make it back up my driveway.

This brought me to find that the charger wasn't staying on for more than about 30 minutes or so. After letting it sit for a while after that I tested the pack and saw just under 36v. Long story short, I found a bunch of crappy corroded wires and replaced all of the bad ones. I cleaned contacts and also tested each batteries individually. Here are the results...

6.35
6.34
6.20
6.25
6.27
6.28

This seemed good from what I've heard but I'm still not convinced that they're OK under load.

I have a powerwise charger like most others. The cart is a 2005... I've been pulling the charger cord and putting it back and it will charge for another 30 or so minutes. After 4 or 5 of these cycles, and waiting 9 or so hours, the pack ready 36V or 37V. I've done this a few more times but haven't taken it back out for a test drive yet to see if it feels any better...

I've cleaned the contacts on the receptacle a bit and looked inside its box on the cart and it looks ok to me...

So my questions...

1) Any thoughts on what this might be? or what I can check to drill down to the problem? I wish i had another charger to test but I don't.

2) After a charge I can hear the batteries bubbling or whatever and they leak a little bit of water onto the top. Does this mean they are overfilled? The previous owner said that he topped off the batteries to just above the plates (wondering if he let the level drop much below the plates which worries me)

3) The only reason I made the trade was so I could turn around and sell this easier than the motor that I was selling. If the batteries are bad, should I insist he take the cart and simply pay me the $2k for my motor? Or would I still be able to turn a profit buying new batteries and selling the cart?

Any help would be appreciated and please let me know if I've left off any important information. Thanks in advance!