Hi, interesting. You mean this "block", right? I can't find a higher resolution pic of it at the moment. Would it be worth cleaning in IPA or just replacing? If a transformer for example surely it would work or "not work" and nothing inbetween, would it? I did check those connectors were tight but for the contacts themselves, I have no idea. Ta!
You can take the contactor apart and clean the contacts with a file or sandpaper.