This vehicle recently had its radiator changed, and ever since, the hood won't close. I've found that if I shift the level manually, it will close, but otherwise it won't. The spring appears to be working perfectly fine, but for some reason, it just won't pull the lever far enough to allow the hood to close completely. I've tried greasing it up, tightening the spring, etc, but it still just won't budge. What can I do to fix this?
It is likely that something has been pushed out of alignment during the repair - you need to inspect for things in that line of thought - look for places where parts have been rebolted/tightened and they are not exactly as they were or something that has been twisted etc.
I make the assumption you are speaking of the latch mechanicals - which are often removed/moved during a radiator change - and are often located on top of or a part of the same structure that holds the latch/radiator. Look for ways to make adjustements there.