I have an Abbott brand 'electronic ratio adaptor'(ERA) in my '89 with an automatic. The ERA was dead on accurate with my speedo gear meant for a 2.59 and ERA set for a 3.33. I now have a 2.59 in the car and want to keep the ERA in case I make changes later. How can I set the ERA to neutral so my speedo will be accurate with the 2.59 gear? Any info would be appreciated. Thanks.