FCT Bolt/Knob Fell Out

[h2ohangtime]

The retaining ring on the spring-loaded bolt that secures the top part of the FCT to the lower part came off. Now, when the tower is down,the bolt won't stay in the hole. What is the process for getting the retainer back on the bolt? I tried compressing the spring with thread and zip ties, but I still can't get the retainer back on the bolt within the small working space of the tower sleeve it fits in. I tried removing the knob from the bolt, but it didn't seem to want to budge, so my guess is it's a one-piece unit.

Any ideas? I have a hard time believing this is the first time it's happened...

Thanks!