<<...It seems the early rotors had the mounting holes drilled such that they
were not
exactly 120 degrees apart around the circumference. The holes could be
aligned with the matching holes in one position only. If the bolts were
tightened with the the rotor in one of the two "improper" positions, they
stressed the rotor such as to induced the failure. This was on very early
models of the brake. ...>>

Hmmm.  I recall the rotors only fitting one way.  Didn't think it was
possible to put them on incorrectly.  This does sound like it may be the
problem.

The new owners of MATCO (asset sale) have no records of the previous
company's and won't honor any type of warranty by the former company.  They
did offer a slight discount and wanted to know more info, which I will
supply.

Naf
LNC2 N7PN