I've helped many to solve issues with a Ray Gingerich RO, unfortunately I'm not seeing an answer. Have you changed anything since last year? What do you have the 2 needle valves set at? The big one should only be open (closed is fully clockwise) about maybe 1-1.5 turns, for now fully close the small needle valve. If that won't give you pressure you may need either a new high pressure pump or a new needle valve, as long as the U shaped gaskets have the open side to of the U face towards the membrane, not towards the top.
How old is the RO? Once you show pressure on the gauge by the pre-filter, do you notice any change in the flow out the concentrate and permeate hoses when you engage the pressure pump?
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.