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We see this question all the time here and about 90% of these are battery issues. When was the last time you had the batteries serviced and load tested to be sure that they are good and not failing? Do this first and even if these are brand new. Even new batteries fail at a fairly high rate. IF one goes bad it drags the current out of the others. If they are over 3 years old OR you haven't been checking the water frequently, chances are good they need replacing. Hope this proves helpful here. Please get back to me if we need to dig deeper into this as all follow ups are included in our fee. No time limit.
You mentioned "slides" and "levelers" in the question........now just one? I have to leave shortly so I can't do a phone chat right now and I will opt out so another tech can offer something on this for your or perhaps take a call.
Have the batteries load tested and be sure one isn't failing here. This points to that above any other reason. In my shop it is the first thing we would do before anything else. Just taking a voltage reading doesn't tell you the actual condition. I will be back in a few hours if you still need some assistance here.