Learn or Burn #1:
After 45+ years working with electrics, people ask me what products helped get me here. Brand callout warning: no sponsor pays me, I buy these products. Either I was burned by lesser products, or somebody shared a success story. Only a product that has earned its keep with me makes the Learn or Burn list. #1 is Caigs DeoxIT D-Series Contact Cleaner and Rejuvenator. A tiny bit goes a long way. It cleans terminals and improves electrical connections, then stays put to lubricate and protect.
I get mine from the source at http://store.caig.com/s.nl/sc.2/category.188/.f