Omega Prolab 4x5 problem, stuck at the top of the column

Hi everyone,
I was working with this omega enlarger and raised it really high. Then I wanted to lower it. It's stuck.
I can raise it higher, but not lower it beyond a certain point.
Not sure if there's a certain lever I need to push to lower it all the way or the enlarger is malfunctioning.
Please help!!

Thanks!

I vaguely recall having similar trouble years ago, related to the counterbalance springs on the rear of the shaft sticking. The manual states that they should be lubricated occasionally. If they are are full extension, maybe they are stuck? The manual I have doesn't contain a diagram that shows them, unfortunately.

At full height the springs are fully wound into their housing.
Is there a possibility that the body has slipped onto the top of the column. It may be a fraction of an inch but enough to hold it in place.
The fix may be to tip the top of the head/carrier too the front as you lower it.

Thanks guys, I figured out the problem. There's a metal plate thing on the front side the of column that was detached and blocking the enlarger head from being lowered. I pushed it back into place and the head moves freely now. While checking the enlarger, I see out of two counterbalances, only one is attached to the column. I attached the other one too. However I am a little curious because it seems to work fine with either one or two counterbalance.