Galion 150A crowd cylinder issue – probably very bad

I've gotten a lot of valuable information off this forum over the years. But nothing like this issue seems to be discussed. I have a Galion 150A with a 3 section boom that the main crowd cylinder works fine but the two inner ones won't move. We removed the two hoses to the inner cylinders and no oil comes when operating the valve in either direction. We blew air back through the hoses and could hear it getting to the oil tank. I don't remember if we had to operate the crowd valve to let the air flow. I have the operator and shop manual but they are of no help. The valve appears to be working since the main, outside, cylinder works. The maintenance manual shows the hydraulic manifold removed from the rotary joint. There are only two ports. So the oil to all 3 cylinders flow out of the same ports on the valve into the rotary joint. But there are four separate lines leaving the rotary joint under the boom. Two to the main crowd cylinder and two to the inner crowd cylinders. Its hard to believe the rotary joint is the issue. It appears the oil goes in but does not come out to the inner crowd cylinders leaving the rotary joint. if it had a massive internal leak you would think the main crowd cylinder wouldn't work. But I don't know where else to look at this point. The shop manual doesn't address the rotary joint in any detail. It looks like the whole boom assembly needs removed to get at the rotary joint. I don't know if I want to tackle that task. Thanks for any help on this problem