The 2004 Sunlines had the round hinge. I even have a 2004 T1950 apart in the barn.
Here is a pic of my 2004 T2499 roof vent hinge so you can see what it looks like. Sunline gave me 3 new vents under warranty to replace these bad fast rustings ones.
Here is a link to one retailer who offers the Ventline BV0554-01 replacement cover for the original that was on there. They have a lot of pics of what the dome looks like. Scroll down to see them. Amazon and a lot of places sell these too. I have bought from Etrailer in the past and had positive experiences. Shop and compare and don't forget free freight or charged freight.
To undo the cover, you take the inside shroud down so you can take the screen out. Then loosen up the crank lever from the metal mount and unhook it from the cover. Then up on the roof, using pliers unbend the curled tab on the end of the hinge and slide it off the hinge. The curled end tabs hold it from sliding left to right.
Heads up in case you do not know! The roof is not a "direct" walk on roof. You have to take precautions to protect from falling through the roof. Using a tarp to protect the rubber then place small sheets of plywood at least 24" wide to span the rafters. Like this. A solid ladder to get up there
Then small 2 ft x 4 ft sheets of 3/8" or thicker plywood
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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