2005 Merc 6hp lower stuck in gear

[spencergross]

My 6hp was coming out of gear at full throttle, so I undid the little bolt behind the rubber grommet on the side to try and see if the shift shaft had to be adjusted. Then the gearbox somehow got stuck in gear, and even after dropping the lower unit and manipulating the shift shaft I can not get the lower unit out of gear, it's almost like moving the shift shaft doesn't really do anything. I'm quite lost so if anyone can help I'd really appreciate it.