Yeah, that's exactly what I did (took the hose off). Light shined through, looked good overall - was expecting some buildup of some kind, but nothing really.
The odd thing was, the one time I did get it to light all the way through, it was only for a moment, then the ball of fire happened - if I had been inside preparing the meat it could have ended really bad, (which I would have been if I didn't come back out to make sure it was still working).
But yeah, now that I think about it there's really no way to get a brush in there unfortunately.
Once I have the assembly out I'll bring it over to my air compressor just to verify it's as clean as I thought it was. Customer service thought blowing through a straw would suffice, so I can't imagine it's the tube causing the issue - but I've almost been wrong before.
Edit:
I just got off the phone with Weber, they were concerned about the ball of fire I mentioned and are sending a new regulator/hose assembly and also a burner tube just to be sure.
Overall, great service from Weber.