I did a write up on this a while ago with pics. To get the o-ring properly seated to prevent moisture in the future, you need some silicone lubricant on the o-ring and it will pop right in correctly. It is possible to get the assembly back together with the o-ring not seated properly. Been there, done that.

Here are the pics I used: https://www.crossfireforum.org/galle...y.php/cat/2004

James