Stroke Deficiency?

[[old] fiftyeggs]

Been erging close to two years, about 40K a week. Recently found a small contusion a couple inches below the tail bone, sorry to get graphic here, but its inside the crack and to the right. I'm wondering if this is maybe an issue with my stroke, like am I leaning back too far, pulling to the right, or maybe sitting too far forward on the seat. For reference I row on slides, and do mostly long slow rows. Thanks.<br /><br />Barry