Just FYI, I found this repository of Priam documents, photos, and EPROM dumps:
http://bitsavers.trailing-edge.com/pdf/priam/I can't see how you could align the R/W heads to the servo head in such a design (sealed HDA). AISI, the heads are designed to be assembled without regard to physical alignment. The servo surface would be prerecorded with special dibit patterns, and each of the R/W heads would be aligned via a low level format. This is in contrast to a removable disc pack where all R/W heads must be physically aligned to the servo head to ensure pack interchangeability.
I can only relate my experience with the latter design, specifically Control Data's removable SMD drives. These had a dedicated servo surface and 19 R/W surfaces. The actuator was a linear voice coil type with the heads parking on a ramp. Each head was fastened to the headstack via a small Allen screw. There was a longitudinal adjustment slot in the side of each head with corresponding alignment holes in the casting of the headstack. A tool shaped like an old sardine can opener (ie a key), with an eccentric nipple on the end, was inserted through the hole in the headstack and its nipple engaged the adjustment slot in the head. The fastening screw was backed off to a prescribed torque, and the tool was rotated CW or CCW to drive the head either toward or away from the spindle. A special CE pack was used for this alignment procedure. The technician would observe the dibit pattern on an oscilloscope while moving the head until an appropriate "cat's eyes" signal was obtained. Then the fastening screw was torqued down.
I don't know how you would approach your problem, but in my case I was able to avoid using an expensive CE pack and disc exerciser by utilising the customer's own software pack and a machine code utility I had written. My utility would command a seek to a specific track at the centre of the disc, and would then read the ID from the target R/W read. The reported ID might be one or more tracks away from the target, in which case I would move the head in the appropriate direction while counting the required number of maxima and minima in the data pattern. The console would beep when the head was on-track.
An SMD disc exerciser is pictured here:
http://www.hddoracle.com/download/file.php?id=1491&mode=view