Adjusting Hyd pressure to the Aux

[QwikDraw]

Can anyone tell me how I can adjust the hydraulic pressure to the auxiliary on a Mustang excavator?

The previous owner had a thumb and I was told sometimes people turn down the pressure down to avoid damage to the thumb or bucket...

Thanks.

 

[Dirthog]

The will be a relief valve on the valve for the aux circuit next thing the system must be set below the maxium. All thumbs are so you don't bend cyl we have to set every new machine we install a thumb on down in most cases it is less than half of system pressure usualy around 1800-2100 Psi