Your IPTO pump filter is clogged. On my 150, I could lever a 2x4 against the PTO shaft and stop it. There is a small plug near the lever where you can install a pressure gauge, should be 125-150 PSI. Mine was down to 35 PSI.
Now the really bad news, you will have to remove the top-link cover to get to the filter.
I'll post a picture for you in the morning, I'm on a tablet and the pics are on my computer.