Master cylinder troubles

[a24vc]

I did a 5 speed swap on my truck. Ever since I put the master cylinder in the firewall I push it through at least once every other day. I have to say that it is getting quite annoying. Has anyone else had this problem or does anyone have a solution on how to cure this annoyance??? When you twist it it doesn't seem to "lock" in very well. Almost like its worn out

 

[a24vc]

Nobody has ever had this happen to them???? I find that hard to believe. Especially that no one has had a smart a** comment about use the search function

 

[K204DR]

did it have the rubber ring on it? thats supposed to keep it in tension.