I just picked up a new Garmin Montana 650t to replace my Zumo 660. I am concerned that the battery cover may not be sealing effectively because it does not seem to lock in like the cover on my Zumo 660. On my prior unit, once the cover locks into place, it is rock solid and does not have any play. On the new Montana, once it is "locked" into place, it is more "squishy" and has a bit of play if I put pressure on it or try to move it laterally (i.e. it does not seem to lock solidly into position like the cover on the Zumo 660), which does not inspire confidence that the unit is truly waterproof. Is this normal for the Montana, or should I make the effort to send it back for another unit prior to getting this one set up the way I want it. I don't want it fail due to water damage during a long journey. I spent a lot of time searching the forums first (and found a lot of info regarding battery error messages and the potential need to place an earplug under the cover) however, I could not locate any comments on the specific issue of battery cover fit potentially impacting the waterproof quality of the unit. Thanks in advance for any available info on this topic.