The 62s has an internal memory of 1.6gb.
So unless you have allot of tracks, I doubt that is your problem.
Are you saving the track before you turn the unit off?
Are overwiting the previous track?
On mine I also have a 8gb microsd card and save the track to the card.
Download "Basecamp" from Garmin, after each hunt/hike upload your tracks. You can also reverse that and set way points in "Basecamp" then download them to you 62s.
It is great for new areas.