My experience has been if you use the 180 loop around and blow straight down into the gutter, as stated, you get totally messed up and it wants to wander, making moving along the gutter very hard. If you use a 90 degree turn off the 180 and blow along the gutter it's basically impossible to keep the hose from immediately moving along the gutter (think of the bent end of a backpack blower only 10 times as bad). Last, what did work for me (marginally) was to use a "T" hooked to the 180 loop. This setup now blows air in both directions, therefore canceling the effect of the tubing to move left or right in the gutter. FWIW, even though I had the tubing hooked up to an 8hp little wonder WB blower, hand cleaning did a much better job.
Pete
Pete