You can check you midnight routines in LD 22 - PRT, OVLY. the prompts under DROL are the loads that will run at midnight. For CPUs to swap you will need 135 in there. You should also have at least 30, 34, 60 (if you have t1s), 43.
If you have the new PII system the cores will not swap at midnight.
To add a load to midnight:
LD 17
Req: Chg
Type: OVLY
DROL: <-- enter the load you are missing
<cr>
then you can test
LD 135
MIDN
and then logout
Check with your vendor and find out why they don't want the cpu's to switch - maybe there ia a problem with one. If so find out what there plan is and when they will replace the problem part - they may have just forgot about you and your problem.
Also, as mentioned earlier - make sure cnis are enabled on the face plate and in software, and the cpu's are not in Maint - either active or standby. Run tests on them before swapping.