As a roofing contractor, i find that sometimes the flashing "drops" into the 2" gap preventing the sheet from sliding back up. If this is the case, push the flashing up with a broom handle from underneath while someone else pushes the panel back up.
Alternately, a real good dose of lookin at will sometimes let the answer unfold and the solution will be so obvious you'll stand there and say " ohhhhh! i see.
Andy
August 2007