You are using the *ohms* scale which will only work on the DS junction, both ways, because it´s *resistive*
Indeed you found 70/72 ohm which sounds reasonable.
But both DG and DS junctions are DIODES and have to be tested on the DIODE scale.
A functioning FET will show OPEN 1 way and "1 diode drop" (about 700mV) the other way.
But I guess you are pulling all components, one by one, and testing whether they measure normal or not ... that is not the best way to find problems, by far.
You must *troubleshoot* it, which means checking what *works* or not, what controls affect what, then do some voltage measurements, and only IF troubleshooting leads you to a suspect component, you measure it.
Ok, which amp?trying to find the problem with a guitar amp
Pulling parts at random is the same as having a car problem and fully disassembling it, then measuring part by part checking tolerance, steel hardness, etc.
What if the car was out of gasoline, oil, water, or battery was discharged?