as above there are a few people on the ukgser forum that appear to have the same issue with this particular version of the zumo, the issue being that the unit seems to avoid major roads no matter what the settings are, but will follow a route sent to it using basecamp or mapsource with no issue,
Could anyone confirm that this is an issue or not, below is a link to the forum thread to see what has been tried and discussed if you wish to look.

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