Just purchased XXL 540TM. Have been reading about problems with map updating because of not enough free space. Suggestions have been to delete current map before updating new one. Is this the correct way to go and if so, how do I go about?\r\nWhen I go into "manage device" via TT Home, I can delete items on the computer but not on the device itself (that button is greyed out). Any suggestions?\r\nThanks.