Scott,
A little background . . .
The Brite Box plug we make for the 9004 / 9007 bulb is made of a different material than the stock plug. Why? Because of a four letter word that starts with "F" - Ford. The factory Ford headlight plug is notorious for it's terminals losing their "spring". This loosens the connection to either the Brite Box's female connector or the headlight bulb if there is no Brite Box installed. The looseness of the Ford plug increases resistance, and therefore current draw to go up. The result is a melted plug, Brite Box or not.
In response to the problem, our plugs are shot in a high temperature material that can withstand the situation listed above. The only drawback is that the material is more brittle than ABS plastic stock plugs, hence the problem you have experienced. All you have to do is call and we will send you a replacement plug.
Respectfully Submitted,
Joel Toy
Baker Auto Accessories
970. 879. 4201
thebritebox.com