Thanks for the responses. I had not gotten as far as man-handling the config files like Bruce suggested. Doing that today does not seem to help the situation. I also explicitly listed dasd_mod_diag (and the rest) in /etc/sysconfig/kernel and then re-ran 'mkinitrd' and 'zipl'. No joy. (The driver loads. It just does not have an affect on the disks.)
I added four minidisks formatted for CMS (all 4K blocks). Was unable to switch those into DIAG mode either, so it does not appear to be a CDL or formatting issue. The hunt continues! -- R; <><
