No hydr. pressure on Bobcat 853 startup?

[OILBURNER]

Hello folks, I have a trusty old 853 Bobcat that is trying to tell me something, need help figuring out what.
This past weekend I fired it up, and hopped out of the cab to do something else while it was warming up. When I was headed back over to the machine, I saw it visably 'lurch' in place putting pressure on the parking brake. I kinda thought 'huh' but I knew the fluid level was good & everything looked ok in the cab so I worked her a bit.
Next day, I had a helper in the cab, and when he started it he said he did not have any hydr. pressure & the * light was on so he shut it down. I rechecked everything & all looked good, so I had him start it again. Same thing = no pressure and the hydr. light was on, then the machine jerked a bit, light was out, and hydraulics working normally. We shut the machine down several times during the course of the day, each time it started back up fine with normal hydraulics
The following day I started it up cold, the * light was on + no hydraulics so I shut it down.

This is likely one of those questions I won't like the answer to, but I gotta know...
Can anyone help diagnose what's going on here? I sure hope the hydr. pump isn't crapping out on me
Machine has ~2500 hrs on it, new hyd filters last year.

Thanks -

 

[crewchief888]

check your drive belt

:drinkup

 

[super mechanic]

When you said no hydraulics ,do you mean no lift and tilt?and drive was ok ,
or you mean no lift,tilt and drive? 853's they have 4 pumps,1 gear pump for lift,tilt and aux.
2 tandem hydrostatic pumps piston type and 1 charge pump geroller type.

 

[equip guy]

Check seat switch, and lap bar sensors, Had similar problem, and seat switch kept turning on safetys