I have always noticed in shady areas of St. Augustine my mower will leave stringers. I have narrowed it down to the blades of grass being weaker and therefore get pushed over. My mower just doesn't have enough vacume so its missing and leaving stringers. If I lower the deck I won't have any problems. but then the turf starts to thin. My buddy has the same mower as me and he has the same issue. I should get with him about it. Anybody else in Florida have this problem? Seems like the eXmarks don't have this problem.