JD 435 Bale Density Valve

Good evening all, havent had this baler long, makes pretty decent bales, however running through some checks and after replacing the faulty density gauge with a actual pressure gauge that works I have found that after closing the bale chamber the pressure slowly leaks off. I have manually checked the cylinder packing by removing the lower hose and applying pressure to the cylinder and they seem absolutely perfect. This is where it gets really interesting. With the lower hose removed on the RIGHT HAND TENSIONER when I close the gate and apply pressure to the cylinder the pressure rises to around 1200 psi and then hydraulic fluid begins to gush from the hose, not the cylinder, the hose. If you remove the LEFT HAND side hose and do the same thing there is no fluid backfeeding into that side. This is quite confusing and I seemingly cannot find any info as to how the valve is supposed to flow, obviously this cannot be correct. Hoping someone with experience of these Density Valves will be able to help me. For reference the sides I am calling Left and Right are looking at the front of the baler. Also, if anyone has a Technical Manual for one of these balers or a scanned copy it would be greatly appreciated.

JD 435 Bale Density Valve