: Google Books might have a preview or the full text of the Mantra Mahodadhi translation. Searching for the title along with keywords like "English translation" or "pdf" might yield results.
The most respected English translation is published by Sri Satguru Publications (Delhi) as part of the Sri Garib Dass Oriental Series . You can find it at retailers like Motilal Banarsidass and Exotic India Art . Overview of the Guide Mantra Mahodadhi English Translation Pdf