John deere 225dlc. Big boom sometimes won't go down. Where do I start
With a machine serial number please. Unless you have the controlled lowering device option, then I would be starting with the boom reduced leakage valve. I would remove the poppet and run the machine. If the issue went away, then either the poppet was sticking, or the poppet's pilot control spool is sticking. NOTE: make darn sure the boom is on the ground and all pressure is relieved out of the boom circuit before removing that poppet cover or poppet.