The glass is clamped solidly into the aluminium frame. It the entire frame that is tilted via the switch rather than just the glass. The glass does not have any contact with any moving parts.
It looks to me like the ball and lever ends are push fits. All be it pus fits that went on 40+ years ago - they are pretty solid. Can;t see any reason why they cant be switched though.
No idea which was original to a 40 sorry to say.
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