How was the R80 (etc) HDA assembled?

How was the R80 HDA put together at the factory? From reading the printsets, (R80, RA80, RA81, RA82 -- they all have similar HDA designs), I believe that the spindle and platters were assembled in the lower half of the 'clamshell' housing, then the upper part put on and bolted down. Then the positioner/heads were fitted via the front aperture and bolted in place. Then the head cables were plugged into the preamp board on the front cover, this put on the front of the HDA and fixed with the clips. All in a clean room of course. Looking at pictures of an HDA without the top cover (search for RA80 HDA on Google), I wonder how they fitted the positioner without damaging the heads. There are 2 heads per arm per side on an R80/RA80. There doesn't seem to be any way to insert a tool to keep them all off the platters. Or was there? Surely they didn't scrape them over the disk surfaces? Anyone know? I am not thinking of stripping mine, I am just curious.... -tony