my forklift has been getting sluggish,there is a three color power gauge on the dash and even after a full nights charge, it shows yellow and red can someone please tell me how to get it back to green ive put water to the recomended level, and that doesnt help, and today i took a reading from the power cord and i got 39v how can that be? the model i have is 36v. how do i test each individual cell to see if its just a few cells or something else mechanical, any help would be greatly appreciated