Two post lift won't lower - any ideas on the issue?

[scottv]

It's a Revolution 10k lift made by Rotary. So I was lifting the body off the frame from above by using straps on the arms...anyway, so I don't know if the load got uneven or what but the lift would go up but would not lower when I activated the lock release and pulled the lowering handle. I do notice one of the steel cables that runs from the top to pulley at bottom of lift has some slack in it versus it being taught on the other side. Just thought I would see if anyone had any idea of an easy fix before I call service. Also, I did get the body off by other means so the lift has no weight on it now. Thanks!!