I am not aware of any Mfr that will service out of warranty units.
Well, yes my EC was out of warranty, but I was willing to pay and EC is the only repair facility that can properly fix the cap and they know that.
Arctic Fox has great customer service and will service their older campers as will Lance.
EC and AF are both heavy campers, well insulated, aluminum framed and for the most part well built. If you go with a pre 2011 EC double check the cap and make sure it is totally glued down from top to bottom. If it isn't glued, walk away.