Outlaw28

ok so ive had probs with loosing 5th gear past few weeks and keep tearing apart my t5...the ring that holds the top gear on keeps coming out and the gear moves back...well i solved that prob it not going anywhere now...but im now getting a vibration...not just in 5th but in neutral its speed related...once i get to about 50 mph start getting a vibration...never had it before until i pulled trans and fixed the ring...nothing visibly wrong with trans...bears feel fine...i cant figure it out...im really getting tired of pulling the trans...anybody got an idea whats wrong..???