I’d check with Gorman to see if they have an oversized packing expressly for this condition. Gorman also has a packing with a teflon ring in one seal for tight packings as well. Is there a possibility the reservoir oil is old? We had a Dover 5” jack that once we wiped the piston down with a solvent it ran fine, but several runs later the hard breakaways and chattering leveling was back. New oil was the answer. I’m no oil expert, but that experience tells me oils can loose their ability to lubricate.
