Clean the bolt holes out. If there is any lock tight in them the transmission can be hard to shift. But you should be able to shift the transmission back and forth a tiny amount to set gear mesh properly with either spur gear. On very rare occasions (rare with the e5, common with then older e6/7), you may have to use a jeweler's file and elongate the transmission holes a tiny bit to account for the movement needed. It only takes a few good swipes, so be careful and check often.