Hy Lode51, I just read the disassembly procedure, and the mainshaft should not be stuck to anything once it is free of the rear bearing. the mainshaft should be able to slide out through the sychronizer drum, first/reverse gear and second speed gear. Once the mainshaft is out of the case the rest of the gears that fit on the mainshaft can be removed. If something is seized together then I guess that transmission is not good, you can return it for a refund or exchange it for another.
