What are we missing? Quick pressure drop

[Bryan_from_MA]

I am working on an orphaned Autojector 200 injection molding machine. The problem is on the mold, the pin pressure holds constantly (within 1 or 2 psi, typical transducer error) at 1178 then without warning or change of state with anything, drops like a rock to 0. We confirmed it with a gauge to rule out the transducer. It uses an isolation solenoid, so once the pin circuit is charged, the load can be taken off the main pump and it runs unloaded at 92 PSI. Attached is the picture of the isolation pin solenoid. Everything has been replaced. A few controlled experiments, like plugging the drains, and jumping around certain things, we've ruled out a leaking -to drain function or state of logic. The only thing left I can think of is something really outside the box like a transient blip on the spool opens the spool into charge mode, but with the system pressure being at 92 PSI in the unloaded state, it would drop the pin circuit out instead of charging it.

 

[Stick.]

Can you post the entire page of the schematic in a high enough quality that we can zoom in on this section, as well as see where the connections to this solenoid go?

When you say the pin pressure drops from 1178 to 0, does that refer to actually 0 psi, or just a low pressure near zero? Is the gauge you're measuring with precise enough and zeroed properly? I want to know if it's possible that the zero you are reading could actually be 92 psi. Where are you measuring these pressures (what point on the schematic)? When did this problem start?