Replacing 30 amp shore cord due to "low ac" message on marine ac unit

Being the good guest that I am I swapped the shore cord recepticles to my friend's boat as the burnt receptivle was causing low voltage which in turn was causing the cruisair air conditioning unit to stop working with error message "low ac". This fixed the issue as well as prevented a major fire hazard. Also, while I didn't have any petroleum jelly, reccomend slathering all cinnections in it to prevent corrosion.