Hydraulic Pressure Valve Location??

I have a HT27 and I'm wondering if anyone knows if there is a pressure valve that you are able to test the pressure in the hydraulic drive system on the HT's and if so, where it is usually located? I have a mechanic who is able to test my system for me to see if there's a fault but I don't want to waste his time looking for where the valve/pressure test point is if someone has any guidance or suggestions it would be greatly appreciated.

Thank you.
Buffy