"depending on how wide I leave the grapple open, sometimes it will bleed down. This would be that the cylinders are in "Series" and just pushing fluid back and forth?"
Ok this bleeding down by its own weight, even though the hoses are hooked together, tell's me your seals are not very tight in the cylinder.
When you reseal a cylinder with new seals and the cylinder is within specification, you will struggle to pull the rod out by hand. It really takes allot of force.
Now this is not 100% way of telling that your seals are gone in cylinder, but its a pretty good indication !!
In the grapple its only a very small volume of oil, it only takes a small couple of drops to leak between the seals in your cylinder, and it will drop your pressure internally by quite a bit.
I was thinking more about the pilot operated check valve today, and it would actually be a good idea to fit.
This will not solve your problem with leaking seals in your cylinder.
Adding the pilot operated check valve will add some safety to your grapple. The last thing you need if you blow a hose is to be dropping your load, especially if someone is near by.
All the best :thumbsup:
Duff