While this guide covers 95% of the "Gateman V20 manual," you may need the original print layout. Unfortunately, Gateman (acquired by Allegion) no longer hosts the V20 PDF on its primary site, as it is a discontinued model.
Warning: Many third-party sites will ask for a credit card for a "premium manual." Do not pay. The Gateman V20 manual is free and available via the sources above. gateman+v20+manual