This has me baffled. My 88 BII eats brake light switches about every 3500 miles. When you do a bench check the switch ohms out fine, but somehow it wears on the pivot point so that when you step on the peddle there is not enough movement of the switch plunger to make contact. The only thing I could think of is the rod coming out of the brake booster is worn, I rotated it 180 deg last time I changed the switch with no real difference in results. Ideas?? 
