My 1900AE has this same problem. The safety is its own spring, intended to locate the 'nub' on the back with the two depressions in the frame. My 'nub' is worn and the safety tends to 'flop' a bit.
I don't know what could be done to correct this. I don't intend to try bending the safety itself.
Maybe someone like Thor could suggest a 'fix'. I imagine he's run into this problem in many of his restorations.
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I like my coffee the
way I like my women...
...Cold and bitter... 
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