i realize this post is about a month dead, but for anybody who happens upon it..
i recently got my current 03SE7 a couple of months ago, PO informed me that the rear roof didn't work and did leak.
during my testing, i routed the motor leads from the front switch to the rear motor.
when powered from the front switch, the rear roof tried to open but failed while rising. i closed it fully, hit open again, and it made a little noise that sounded like mechanical energy being released, but it opened!
i then restored the electrical configuration and reconnected the rear roof to the rear switch, and it continued to work. i believe that the roof was jammed (or corroded) shut.
perhaps the wiring to the rear roof cannot sustain sufficient amperage to break loose? perhaps the leaking had corroded some of the electrical connections?
your mileage will definitely vary, but it's a SUPER simple test to perform and paid off big time for me