If you go to that level where powerless Spidey is walking through the city, you'll find a broken seeker in one of the alley ways. You don't have to look hard, it'll be in front of you as you follow the path.
Alternatively, there's another one in one of those Oscorp secret lab levels that appear on the map. I forget which, but it has a circular platform in the middle and the seeker is under it.
That was one of the last things I had to do. Unfortunately the 100% reward is a black version of the new movie suit... why would I want that? Least desirable costume yet hardest to attain. Rather than waste slots on black versions of the same suit, they should have simply added a feature to alter the color of existing suits. If that Negative zone suit was red and blue I'd use it all the time. It'd be my definite favorite. Love the big fat back spider.