/vr/ - Retro Games

I recently acquired this sexy bitch, a Grundig ST 70-750 text (pic is from google). I tried RGB on it and it's as good as it gets. But apparently it holds some grudge against 60hz or something. 50hz fills the whole screen, as it's intended to do, but 60hz adds these huge black bars instead of stretching it. I think it does this to keep proportions (since it's a lower res) at the expense of aspect ratio. I know this is a German-made television set but they couldn't have been THIS stupid to condemn any 60hz signal that came through.
Needless to say I'm seriously disappointed and won't deal with this issue. Is there any way to force the screen to stretch? I have the remote, any heads up from a fellow Grundig owner?