I guess there is some bubbling. I also noticed drops of acid dripping from one corner. I disconnected it from the charger, and opened one of the holes (the ones to pour in distilled water), and put it back on the charger. No dripping, still some bubbling. I think its time for a sealed batter. Any suggestions.
I still plan to fully charge this one to see if the battery is the culprit for the now non functional ES.