I recently bought a Groove Tube for my F-1X, but it didn't fit in the sleeve.  Is this a random hit and miss problem, or are there some tubes that are consistently too wide for the F-1X?

Lots of them are - for most the diameter isn't a spec really, so it's pretty random. We used to have boxes and boxes of tubes that were too fat but otherwise OK.
 
We're using the JJ tubes now - 100% fit!