t6i won't focus through viewfinder at times

[chebo]

Sometimes, the camera won't focus through the viewfinder.  To get it to work, I either have to switch between LiveView and then switching back to focusing through the viewfinder or pressing the Depth Of Field Preview Button.

I've used 2 different lenses and even reset the camera settings, but the issue still continues.

It's a minor problem, but is there anyway to fix this?

[ScottyP]

Not the lenses because both do it.  The DOF preview button might unstick an aperture blade but it isn't a lens thing. 

Maybe be a dirty or damaged connection?  Switching to live view and back and pressing the DOF button are not logically related that I can see so maybe they are working as the equivalent of banging on the camera to remedy a bad connection. Etween lens and camera. 

[ScottyP]

Thinking of things involved in viewfinder focusing.   See if mirror is dirty or if focus screen is dusty or misaligned/loose or scratched. 

[chebo]

I can get it to manual focus by half pressing the shutter button too.  It's under  warranty, so I can just get it fixed.