Yes you can fix without taking primary off. Replace the allen bolt with a regular hex bolt so you can use a socket on it to tighten with blue locktite. The splines aren't damaged in most cases. If it's under warranty they probable won't do this (might ask) but you can after to prevent it fr. happening again. The allen bolt will seem tight but it's hard to get enough torque to keep the lever tight on the spline. It's a good idea to loosen this bolt and the shifter lever bolts at least once a year and put blue locktite on them and retorq. I had a buddy have his come off an 08 with 10k miles on it. This plus the heim joints on the shifter rod are first mod I do.