What is this Columbia supposed to be?

[BillH_NJ]

There is the gap between the turntable and the ring, but the ring also extends past the flat surface of the top about 1/16” or 1/32” on two of the sides. I was also wondering if this was added later and is not original to my machine. There are no washers between the motor and the board, so the turntable probably does sit too high. Does anyone have exact dimensions of the top or the flat part of the top for cases from the different models that might help me identify what the case originally came from?