Hello -- I have a Polyphon disc the exact size of my 11-inch Regina
discs, and I read everywhere that the two are compatible.  The Polyphon
disc has two small drive holes either side of the center spindle hole.
On the Regina box there is one square-ish drive lug beside the center
spindle.

Do I grind out one of the Polyphon drive holes to accommodate the Regina
drive lug in order to play this disc?  And is there a Polyphon disc of
like dimensions that plays a bell box and is not compatible with a
Regina box?

Thanks for your advice.
Tom Sendall