Gilbert,
Under normal circumstances, the brackets are mounted to the wall and then the awning is hung on the brackets. Then an insert is slid in place to trap the awning from lifting up. Safari mounted the brackets with the bolts already sticking thru them to the awning first. Then they install the awning into the cavity thru predrilled holes in the cavity. To the best of my memory. I cut thru the silecone the entire way down the top from front to rear. Then cut thru the silecone on the front and rear ends. After removing the mounting nuts and washers, I installed a block of wood just past the exposed bolts on the inside and used a pry bar to leverage the bolts outward. Seeing how the bolts are trapped between the awning case and the mounting bracket if you move the bolts you move the awning outward.
Once you get the awning out far enough to replace the motor, that would be the time to get a piece of 16 gauge flat aluminum sheet and fabricate a new end piece and install it. Fred