PeterB,
If possible just change it.Chances are that the corrosion has gone up inside the insulation & will follow the wire like current. It'll go bad inside. This is one of My preventive maint. Things. I change them every couple / 3 years. Measure how long,Go to NAPPA or other Quality auto store & get the ends crimped or soldiered on. I use welding leads- Always bigger than needed.Or marine grade (best).
If You use the old then cut back till Clean wire is visible.Weakest link in the ignition system!
Scream'n reels'
Tug
