I mech for a small group of gas/propane/deisel machines, they're on 4 year lease...than we/I start over. While I have bought terminal ends, cut off offending terminals, peeled back insulation and clamped old/cleaned cable in new terminal,even spraying w/'terminal protector'(a lacquor), I would not do this on machines I intended to have to mind/fix for any amount of time...or my own..unless the cable in question was real involved POS. I recommend replacing ENTIRE cable. If it's neg it runs to ground somewhere, remove-clean terminal/areas replace. If pos it (usually) runs from pos post to starter...again, clean terminals/end spots and replace. Said cables availible from NAPA etal in appropriate lengths and colors(insist on proper ones), if in doubt get it wee bit longer.Clean w/chemical cleaner, flood w/water,when dry spray w/terminal protector. Also you need make sure not overcharging/battery boiling over, acid corroding terminals...
FIRSTLY DISCONNECT NEGITIVE CABLE, than positive. When reconnecting, FIRSTLY CONNECT POSITIVE, THAN NEGATIVE.
I defer to CAP1, my superior in all things mechanical..except on my personal vehicles:)