Stop in for a cup of coffee

they have expiration dates on them - I have at least two that I know are past date, they won't fill them

I think that they test them every so often to make sure that they are still safe...

Turn it in and hopefully they will see it's "expired" and go through the testing and get it re-certified....

Find a Home Depot. They have a fully automated set service exchange set up. 20 bucks for a full, new propane tank, simply put your empty in the slot the machine says. The machine doesn't check dates. Easy peasy