Round Three EK 2 frame slot?

[Raul]

Hi,
I would appreciate any info on an IC2 with round three's.
At the three o'clock position on both side is a small flat square slot
in the center under the inner rim at the base (beading).
It is not the the core that has this it is the frame.
I only have a picture of when I purchased it and not of what I am trying to explain
I hope I make sence?

Thanks
Raul

[George Stimson]

I changed the name of the thread to make it more specific to the question.

[Raul]

Thanks George,
Raul