JLG N35 very slow forward/reverse

Hello, new to the forum.-----My boss recently purchase by auction a used JLG B35 lift. We did not see this unit perform b4 purchase. When it arrived batteries were dead, installed 6 new batteries and started to test. Forward and reverse or very slow-the manual says it will go 2.5 mph, probably can only get .5 if that, also is very weak, will hardly go over a bump. Do have manual but not very helpfull in trouble shooting. Checked voltage to contactors in motor area, getting 48 v to and...

JLG N35 very slow forward/reverse

JLG N35 very slow forward/reverse