2004 sportsmen 500
#1
#2
Brass tank insert has spun. Hard to do anything once this has happened. Problem is people over tightened the drain bolt on these plastic oil tanks. Over 200 bucks for a new one,but actually better to find a good used 2001 metal tank on ebay and you won't have to deal with that again.1525 Polaris Sportsman 500 4x4 ATV Oil Tank Reservoir 01 2001 | eBay
#4
2002 is when they had a switch over mid year from the metal to the plastic tanks.Bolted up the same and oil lines hooked up the same on both tanks.I never did like the plastic tanks because of this and also some exploded from pressure build up if the vent ever got blocked. I even replaced a few for customers that wanted the old metal tanks back from the previous year models when I could still get them.Most brought them in for the same problem you're having on the spinning insert. This one came off a 2012 Sportsman 500 that blew out the bottom of the tank.