Hitachi ex 120-2 loss of hydro power

Hey guys new to four posting things in here so be kind.
I have a hitachi ex 120-2 I need manuals for and I need to diagnose a problem I am having.
When I start it for the first time of the day I have great Hydro power it digs and picks up a full bucket of dirt (1 yard) bucket. But here is where I have the issue after about 30min the hydro power starts to get sluggish and then an hour in and I can't pick the bucket up at all until I shut down for an hour or more. Then it works for 30 min or...

Hitachi ex 120-2 loss of hydro power

Hitachi ex 120-2 loss of hydro power