953 LPG 20Z new pump cartridge but weak lift cylinders

Machine had been whining, and a new vane pump cartridge fixed the whine.
Fluid was black, so new fluid and filter.
Bucket tilt power seems ok, but lift cylinders too weak to rip up dirt or lift a good size tree more than about half way up.

Thinking it might be a relief valve, and thinking type 1 valve.
Guessing the lift head end relief valve is the one sticking out horizontal to the right closest to the filter - could I reach in through the filter hole and try cranking it down a bit...

953 LPG 20Z new pump cartridge but weak lift cylinders

953 LPG 20Z new pump cartridge but weak lift cylinders