help please electronic odometer is broken

I have a 1994 Chevy Caprice with an electronic dash. My odometer mileage for the last year has jumped around constantly reading anywhere from 0-999,999
miles. Recently the speedometer will blank out for short periods then resume showing my MPH.Any ideas on what is responsible for this and what the repair would be? Thanks snipped-for-privacy@rochester.rr.com
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