I've had a used 97 F150 for about a year now. I popped the hood last week and now the main latch has failed. I tried spraying some silicone lubricant on the latch since it's got some rust on it, but it still doesn't lock in place. I can't see any broken or missing parts. Not sure how the main latch works either. Has anyone had an issue like this before? I'd rather not have to replace it as it looks to be a little bit of a pain to do it.

 

I've run across this same problem on a couple of occasions on my 2000. The easiest way is to remove the latch mechanism and work on it. You can use a socket and a long extension to remove the bolts through the front grill. Once off, spray it throughly with PB Blaster or the like. You can also use a large screwdriver to press down ito the latch mechanism and get the keeper portion to trip over, then pull the release inside the cab to get it back open. Sorry I don't have pics. In the future just spray it every oil change or two and it should correct the problem.