Have you found the solution to your problem and just not posted? I'm
surprised no one else has chimed in. It sounds to me like your shift shaft(at least that's what I think it's called) is out of place. It's the part that your shifter pedal connects to that sticks out the primary. At the base of the shaft there's a spring actuated mechanism that has to be compressed before it is reinstalled. I believe this has to be done in order for it to engage the shifter drum properly. Pull the primary cover back off and make sure it's installed correctly. The service manual link on this forum should help highlight what I'm referring to.