you kind of have to get the leadscrew disconnected from the gearbox to remover the apron.
So the pin connecting the leadscrew to the gear box shaft is out, correct? you can move the carriage left/right and the lead screw stays put, correct? (i.e. the lead screw is not some how stuck in the apron).
If the above is true, and its put together like mine, I would fashion a slide hammer onto the right end, or even a clamp attached to the right right you tap with a hammer. Start with very little hits - when disassembling I've learned that hundred and hundreds of tiny hits works really well - as well as dozen major blows and doesn't destroy everything in the process. Then the leadscrew just slides out of the apron