i've fixed alot of msd boxes, they're pretty simple. if they won't fix it for ya, drill out the rivets that hold the back on. check the soldered connections for all the wires that exist the box.i've seen alot of the heavy ground and positive cables have cold solders and crack, they'd work intermittently. there's also alittle fused loop that'll burn in two if theres a short somewhere, look for it next to the big transformer. if its burnt in two, just solder a wire across the land connections to complete the circuits. i've fixed at least 9 boxes and all of them had 1 or the other short.check it out, bet you'll find it quik but let msd do it if they'll warranty it for ya.