IBM 6151 Maintenance And Service Manual page 402

Step 4
The problem may be the diskettes.
1. Get a different set of diagnostic diskettes.
2. Try to run the failing diagnostic test.
3. When the test completes or stops, look at the bottom of the
display.
DID THE MESSAGE "DIAGNOSTIC ERROR - Diskette error"
DISPLAY?
NO Replace the failing set of diagnostic diskettes. Go to
"Problem Determination Procedure PIC 0030" on
page 3-0030-1 and get another SRN.
YES Continue on the next page.
3-9860-4 Service Manual