'89 Liebherr 934 Loss of hydraulic controls intermittantly

[Case450]

Hey guys, looking for a starting point or some suggestions........my liebherr 934 excavator is giving me grief.
She was running fine when I parked it. I went to start it the other day and she fired right up but no hydraulics in the sticks or the pedals.

So this morning I fired it up and everything works fine....I"m juuuuuuuuuuuust finishing up my work area with her and sweeping the ground to make myself a parking spot and than the hydraulics just stopped working mid-operation.

Something must be loose for it to be intermittant like that....trouble is I"m not familiar with the inner workings of a shovel and all of my labels are all wore off! lol It"s a used ol" girl I bought for use around the property.

Any ideas of where I should start looking??
 

[AJ.]

The Liebherrs we have in the UK have a safety hydraulic cutout lever that has to be pushed down when you sit in the seat,it stops you getting out till its lifted up and the hydraulics go dead,look to see if there is something under the lever if you have it,it usually pushes a switch,check the wires and switch it maybe loose.
AJ