Strange Crown and Stem Problem with Vostok 2415 movement

[Mattswatch]

I was changing the hands on a Vostok 2415, and when I cased the watch up again, I found I could not return the stem and crown to the movement. What is strange, Is that if I take the movement out of the case the crown reengages just fine. The 2415 has a spring release stem, I am wondering if anybody else has ever had this problem with the same movement or with a similar movement, or has any ideas on how to fix this.

[Nucejoe]

Did you put the movement retaining ring in, to keep the movement centered in the case?  

[Mattswatch]

I fixed it. For future reference for others: I screwed in the crown while depressing the spring very carefully, making sure not to force it in and break something in the keyless work.