Nightmare but now resolved.
The DFM logs are in \Program Files\NetApp\DataFabric\DFM\log
By a process of opening each on in turn I was able to find that dfmserver.log has useful information.
Jun 16 14:30:05 [dfmserver: INFO]: [18312:0x3384]: Logon request for DOMAIN\ACCOUNT (domain\account) denied: 1326, Logon failure: unknown user name or bad password.
Using the time stamp I was able to find that audit.log {open with wordpad} also has a piece of the puzzle:
Jun 16 14:30:05 [Unknown:NOTIC]: DOMAIN\ACCOUNT:API:err:[www.xxx.yyy.zzz]:Authentication failed for user - DOMAIN\ACCOUNT Input API is - <dfm-about/>
Investigation of the server showed Snapdrive V6 and SMSQL v5
Nothing could be found in the SMSQL GUI for the Operations Manager link
However in the Windows registry
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SWSvc\Parameters\DFMConfigParams\ServerConfig
These values should be blank if the server is not 'talking' too operations manager.
Removed vaules and operations manager is no longer locking out the service account.
Hope this helps you out.
Bren