I finally got down to the coast last week after a 2 month break. First cast of the day my entire spool came off and ended up in the drink. I was able to retrieve it, shove it back on and cast it again. Sure enough the same thing happened. The entire spool assembly came off to include the drag nut and everything. It appears that the spool "snaps" onto the shaft. I have tried to shove it on and it seems to be holding now. When I reel the spool is now grinding against the body of the reel. I have pulled it up and it seems to be working ok. I have never had this happen before and I am not sure which part to replace. The entire spool assembly, the retaining clip or the spool shaft. Has anyone experienced this? I may send it in if need be but I think it should be an easy fix. It is a 4300SS.

I am afraid to try it again fishing. You can see in the picture how the spool has came off. Fortunately I had a spare and the trip was great. Thanks in advance for the help.
Justin