Fuel filler door question

[TDS-MN]

Hey All,

OK, so the cold weather has taken it's toll on my truck this week. Have a problem that I've never seen before, hopefully someone can help me figure out a fix for it.

The fuel filler door is supposed to be some kind of spring-loaded thing, that would hold itself open, and then hold itself closed. Well, after fueiling up the other night, I went to close the door, and find that it's just flapping around now, no tension on it at all.

I have a 'quick-fix' using 2 magnets to hold the door closed when driving, and so far that has worked, but it's not the long-term solution I want.

I have not yet had a chance to take a look underneath the fender to see what type of mechanism was there, I figure I lost some sort of spring or something.

Any tips to fixing, or a source for repair parts that doesn't involve a trip to the cold snowy salvage yard?