Have you figured it out yet? It could be something really simple... Last weekend right after backing away from the dock in reverse I thought I lost my transmission as I put it in gear to move forward. The linkage was secure, oil level checked out fine....felt the panic want to take hold as we drifted away from the dock. Then I noticed the shaft nut came off and the shaft slipped out beyond where the splines could engage. I had to take a swim and push the prop end back while my girl tightened the nut back on. She passed the "nut handling" test with flying colors. We were on our way in minutes
I hope your solution was as simple.