If Vortex and Nikon (those in my experience) can clean and adjust focus on their binoculars, I'd bet Sightron could too. That is likely one of the easier things to do in a roof...IF YOU KNOW WHAT YOU ARE DOING...and I don't
. Not with a roof for sure.
I'd just get on the phone and call Sightron, talk to somebody in the service or repair department and see what they say. It might be just a simple warranty issue.
I agree with Steve that one of the draws to a good vintage porro is that taking one apart and cleaning it up yourself is not hard. Maybe a roof isn't either...but these are different animals.
EDIT: I got curious and called Sightron, yes, they say that is a simple, cost free warranty issue. Just send it in with an explanation.