Puzzler.

Thank you for replying.

After prepping for this project I unfortunately discovered there is not enough room to operate a dremel heavy duty metal cutting disc on the black anti theft cover.
This is after removing the black plastic surround.

You mentioned the die grinder bit which makes more sense for this job.
Was this used around the inside edge to enlarge the circular opening?
My tumbler has a broken key in the bottom half and the front part of the tumbler is broken away from the bottom and free spinning.

Also, ours has a decorative thin metal chrome cover over the core which I was told is no longer available. I suppose this piece is not absolutely necessary when installing the new core and anti theft cover.

Thanks again for the reply.