2004 Cat 308B Stick In Issue

Hello All, I’m troubleshooting a Caterpillar 308B SR, serial 3YS00862 (Japanese-market machine). The machine has a Kawasaki main control valve, marked: Kawasaki TYPE: PEC0170-31001 S/N: M917-08008 P/N: 1148-1754 The problem is that the stick will not move in one direction (Stick IN), while Stick OUT works normally. What I know so far: Stick OUT works. Stick IN does not work. Other hydraulic functions appear to operate normally. I initially suspected the cylinder, but I have ruled that out to some degree. The previous owner had apparently swapped the two large hydraulic hoses going to the stick cylinder. With those two hoses swapped, the stick will move in both physical directions, although the joystick directions are reversed. This makes me believe the stick cylinder, pumps, and downstream hydraulic circuit are capable of moving the stick. Returning the hoses to their original positions brings me back to the original problem: Stick IN does not work. I have not yet measured pilot pressure. I currently do not have a hydraulic pressure gauge, but I am willing to buy one if that is the appropriate next test. I have found the Cat 308B SR service information for 3YS00001-UP, including the stick hydraulic schematic and main control valve diagram - But is not matching up based on what I am seeing. The manual identifies four pilot ports associated with the two stick control sections: Pa1 = Stick I OUT Pb1 = Stick I IN Pa8 = Stick II OUT Pb8 = Stick II IN The manual also describes Stick I and Stick II as two sections of the main control valve, with pilot oil operating both sections. Where I’m stuck: The main control valve is extremely crowded on the machine, and the small pilot hoses are very difficult to trace. I have located what I believe is the pilot-port area on the bottom/side of the main valve, but the physical valve does not appear to have the same obvious labeling as the schematic. The small fittings have what appear to be Japanese markings, but I cannot find clear Pa1/Pb1/Pa8/Pb8 markings on the valve itself. There is also a potentiometer just lying on top of all the hoses as pictured, not sure if that could have to do with it, but the wiring is definitely suspicious. I’m specifically trying to determine: Can someone identify the physical locations of Pb1 and Pb8 on the Kawasaki PEC0170-31001 valve? Is there a Kawasaki valve schematic/port diagram that shows the actual physical port locations more clearly than the Cat schematic? Are there known problems on these 308B SRs where Stick IN pilot pressure is lost while Stick OUT remains functional? Is there a way to test the Stick-IN pilot circuit without a gauge, or should I go straight to installing a pilot-pressure gauge? If I do use a gauge, what pilot pressure should I expect on Pb1 and Pb8 when Stick IN is commanded? If both Pb1 and Pb8 have proper pilot pressure but Stick IN still doesn’t work, what would be the next component to check — the main valve spools, load checks, stick relief valve, or the stick lowering control valve? I am trying to diagnose this systematically before disassembling the main valve. I don’t want to start removing plugs or valve sections until I know exactly what I’m testing. I’ve attached photos of the Kawasaki valve and the pilot-port area. The front of the machine is to the right in the bottom-view photo. If anyone has the Kawasaki PEC0170-31001 schematic, a clearer 308B SR hydraulic schematic, port identification diagram, or has worked on a 3YS 308B SR with this symptom, I’d really appreciate any help. Thanks!