I have recently bought an old but servicable MX5 1993....when tested the battery was flat and had to be jumped...this ( a new battery ) then let us down after being parked at an airport for a week...the RAC tested the alternator and it was fine! so a Brand new battery was DEFINATLY fitted... now some 5 weeks later the battery has died again...so I assume there is a drian to earth somewhere...does anyone have any clues on where to look and check for such a drian?