1998 Volkswagen Jetta DISTRIBUT0R CAP & ROTOR CORROSION

WE HAVE A 1998 JETTA, AND AM EXPERINECING DISTRIBUTOR PROBLEMS. IN THE LAST 6 MONTHS, WE HAVE BOUGHT 4 NEW DISTRIBUTOR CAPS AND ROTORS. THE CAPS WILL HAVE 2 OR 3 WEEKS AND THEN EACH ONE OF THE TERMINALS BECOME CORRODED. THEY HAVE A BUILD UP OF SOME TYPE OF "SILVER LOOKING METAL " ON EACH ONE OF THE TERMINALS, WHICH KEEPS THE CAR FROM CRANKING. ONCE I REMOVE THE CAP, SCRAPE OFF EACH TERMINAL AND SCRAPE OFF THE METAL END OF THE ROTOR, IT STARTS JUST FINE. WE WILL DRIVE IT FOR ANOTHER 2 OR 3 WEEKS, AND THEN HAVE TO DO IT AGAIN.

I HAVE ASKED SEVERAL DIFFERENT MECHANICS AND HAVE TALKED TO DIFFERENT PEOPLE AT AUTO PART STORES, BUT KNOW ONE HAS A CLUE AS TO WHAT MAY BE CAUSING IT. I MAY END UP HAVING TO TAKE IT TO THE DEALER, BUT I RATHER NOT. I'M A DISABLED VET AND I RECEIVE A VERY SMALL INCOME EACH MONTH, SO IT'S HARD FOR ME TO AFFORD TO GO TO THE DEALER.

ANY INFORMATION THAT YOU MAY GIVE ME WILL BE GREATLY APPRECIATED