. I do wish the needle was finer, its only ~2/3rds of a turn from high to low.
Any chance you have a flowmeter to hook up to it. The fathom comes with a flowmeter to check your oxygen flow rates through the needle valve. My instructor was jealous of my wife and my units as the needle valve had much finer control than his. His sounds similar to yours. he can easily adjust to fine tune his needs, but the distance from high to low isn't nearly as great as ours. Ours are able to really get fine control down (looking at the flowmeter). I'm still getting used to the needle valve on dives. I'll be diving and either keep noting my p02 getting a little high or a little low and I have to fiddle with the needle valve to get it right, or very often I still forget about the needle valve and spend 5 minutes adjusting with the mavs until my brain remembers the needle valve. We only have 3 hours post class on the units currently, so I'm sure it will come with time.