Awning tilt and arm closure
I came across an older thread, in which the OP had a problem with the awning arm not closing completely on one side. I thought I had the same problem with my awning. It turns out it was "normal," in a sense. My awning has an adjustable angle. This is accomplished by pressing in little buttons on each arm and moving the arm in or out to make the arms longer or shorter (watch your hands!). Making one arm shorter than the other, I can also tilt the awning to one side allowing water to run off . That works fine.
When I retract the awning in the "tilted" position, I end up with the condition described and pictured by the OP, i.e. one arm does not completely close flush with the side of the trailer I can remedy this by adjusting the arms to equal lengths before closing it. According to the instructions for the awning it is OK to close it with a limited amount of tilt. I've driven more than 10,000 miles in the tilted position with no ill effect.
I hope this might be of help to some one with a similar condition.
Forest River SP220 Sport
2013 Tundra 4.6L 4X4 Tow package