I also had trouble with getting the engagement to work, after first spraying them with lubricant to get rid of any grime and displace water and then greased them--they work a lot better now, almost perfectly.
Worse comes to worse, Daniel (bdmontero) on monterosportonline.com forums rebuilds true Aisins and ships them out for free with custom paint jobs for $200 currently. Not sure if he has any currently, but he's really great about quality.
He's just over in Wichita, Kansas if your trip is headed in that direction, otherwise he may be able to next day air it to you.
On a side note, I had to completely disassemble mine also to make sure no parts were binding, that really seemed to help and it helped me understand how these things work...really easy.