Fuel tank pick up

I have problems with my Yamaha 60 2 stroke. On 04 G3 boat. I have taken the fuel line off to eliminate it as a source. ( gas has some water, drained all 12 gallons and noticed a bad smell) the hose appears fine but I had to cut it to remove it so I’m replacing it all. I’m thinking I should check the pick up inside the tank. When I try to take this fitting off it feels like it’s going to twist the entire tank or break the plastic. First, is this worth Checking? Second how does it come off. Maybe I need to hold the lady nut on the top of the plastic?

There is likely a plastic straw in the tank with a screen on the end. Not likely to plug but possible, I've also seen the tanks sag near the pickup and kink off the tube.

I would try to just pull the screws out of the pickup assembly, rather than unscrew the fitting.

I had a problem with fuel, failed one day down river about 5 miles from ramp, took fuel hose from motor and inserted in tank ran fine so knew it was in the tank pick up, back home put a hose clamp on the top of the straw in the take assembly about 6 mo ago, no more issues. hose clam or zip tie don't cost much to try.

I was concerned about the plastic straw like material being deteriorated. I didn’t get it out but have decided that is not it now. Went through the carbs a 3 rd time and finally took it to a shop. Thanks for the replies.