To all who took the time to reply, thank you
Progress to date:
1. Set jumper to 512 k sector on the TEAC.  715/75 recognized it as a different model.
2. It spun the disk upon issuing the "bo P2" command, however, i still got the
ENTRY_INIT =-4 message

I will try to do a net boot next

if that fails, I will try to copy onto the boot 715/75 hard drive the necessary files.  Which leads me to my next question, which files(s) would be necessary for the 715/75 to boot

Would "lifimage" be enough or should i place "rescue.bin", "linux.bin" and "drivers.gz" on the hard drive

Thanks in advance for your remarkable response.

jack dunn