Hello All. I just purchased a 2018 High Roof Promaster (136) and can't find any manuals on line for the Navigation system....there's one for the 2017 but it does not help. All of a sudden the voice that directs you has gone really really low and I can barely hear it. I have pressed every button conceivable and can't find how to turn it back up. Any help would be great appreciated! Thanks! "Freedom"