Most electrical problems of things not working properly are ground related. When fusible links blow that is more a sign of a short to ground somewhere. Lots of juice gets to run directly to ground very quickly. This increased current heats up the fusible link and melts it.
It is always prudent to check and clean the contacts for the headlamp connectors. Also check and clean your ground connectors. But I think that your problem is deeper than this. I think that there may be a short to ground somewhere. Check the integrity of any and all hot wiring associated with your headlamps being on (i.e. running lamps/turnsignals, side markers, headlamps, tail lights, even dash wiring, etc... front and back, everything.)
Electric problems can seem like voodoo. Corroded contacts are much easier to locate and fix than shorts. Shorts may not be apparent and may only be intermitant (i.e. jiggling a wire). If they exist in the heart of the wrapped harness than there may be no finding it without unwrapping the whole thing. If you don't find out WHY the link blew than you'll propably have to live through another blow at some other time. To make matters even more confusing, it could be possible that the link blew simply due to age and fatigue. If you are doubting the intergrity of your harness overall than replacing it with an M&H harness is the best course of action. It is certainly the easiest if not more expensive. Sometimes the cost of the harness is far better than the aggravation of tracking REALLY pesky problems.
Once you find out why the link blew and fixed the problem, repairing the fusible link is no trouble. Simply buy a fusible link from a parts store (links selected by going 4 gauges smaller than the wire it is connected to. If you have 12 gauge wire, you need a 16 guage fusible link.) Most auto stores carry pre-assembled and lengths ready to butt-slice into place. Cut the old link off and connect. Wes V's descriptions and suggestion of an inline fuse connector is GREAT.
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??michael j Team Chevelle Gold #77
70 Chevelle SS396 4sp, Fathom Blue/White Stripes - Canadian built