Just buy a dead board for $20-$30. Buying pieces one part at a time is frustrating because, each time you realize you need something else, you have to look it up and wait a week for it to come. If you spend $20 or $30 on a board with a hole in it, you will have every part you need pretty much so you can figure out the problem in a short period of time. It minimizes the rabbit hole of having to grab one after another after another of small parts.
If you have corrosion near there you likely have some under the SMC as well, I would pour some Kester 951 under it and heat it if it is still acting up after you replace these components(not before removing the trim around it).