I don't have any recordings of Grove from the late 60s/early 70s, but in every recent video I've seen his accent is about as strong as Arnold Schwarzenegger's.

I don't have any recordings of Grove from the late 60s/early 70s, but in every recent video I've seen his accent is about as strong as Arnold Schwarzenegger's. It's noticeable, but it hardly affects your ability to understand what he's saying.