IBM 6150 Hardware Maintenance Manual page 206

Step 9
The diagnostics can be run in loop mode by selecting the Run Test Multiple
Times option in the TEST METHOD SELECTION menu. Run the
diagnostics in loop mode for several minutes on any device you think is
failing.
DID THE DIAGNOSTICS FIND A PROBLEM?
YES
Do the following steps:
1. Record the name of the FRU for each SRA in the SRN. The
FRUs are listed in the most likely to fail order.
2. Exchange each FRU one at a time. Check each FRU by
running the diagnostics in loop mode for several minutes.
NO No trouble was found. If you still have a problem, contact your
support person.
(9/86) Problem Isolation Charts 3-0090-9