I shared a little tip with a neighbor today and thought it pass it on to you guys as well.
It you have a corroded electrical connection ie. rear light cluster bulb holder, caravan lecy plug ect, cover it with brown sauce (Daddys/HP ect), leave for 1/2 hour then wash off with boiling water, then dry with hairdryer or time.
You should now have clean connections and everything works.
My neighbor has just given me some beers as a thank you for saving him money, so we're both happy now