Broken tap

[ANRPiano@AOL.COM]

A customer was referred to me by a very good technician who had the miss 
fortune of breaking a tap while retapping agraffe threads.  The tap broke off 
nearly flush with the plate.  This is a S & S S? circa 1920's.  It is the 
fourth agraffe in the tenor section.  The tap is firmly imbedded into the 
plate.  It will not turn.  I made a tool with two rods to fit into two of the 
four flutes to attempt turning it out.  The rods broke.  Is there a 
commercially available broken tap removing tool?

I attempted to drill the tap out.  My titanium bits did little.  Though the 
grinding bits I used to flatten out the top seemed effective in removing 
material.  Is there a solution here?

The customer does not have enough money for rebuilding the piano (which it 
could use) so removing the plate and coming in from the bottom is out.

My last idea (which I don't care for) is to drill a new agraffe hole infront 
of the old.  There is plenty of room in the plate.  Will this cause any undue 
weakening in the plate, and how badly will the tone on the now 1/2 - 3/4 inch 
shorter be affected?

I know this is not your everyday type of repair, but any input would be 
greatly appreciated.

Andrew Remillard