Oldtimer Cameras of Hatfield, England, should be able to provide you with a Pentacon Six camera and/or prism service manual.  Their website is www.oldtimercameras.com. 
e-mail sales@otcworld.co.uk
Tel +44 1707 273773 (9.30 to 5.00 Monday to Friday)
Even if you can’t find the manual on the website, you can order it.  (You can’t consult it online.)

At the time of writing (February 2010), there is an on-line resource that you can download and that gives guidance on some aspects of Pentacon Six dis-assembly and repair.  It is not the official manufacturer’s repair manual, but has good illustrations and may be easier to understand.  It is currently available here: http://rs366.rapidshare.com/files/29738203/PENTACON_SIX_-_service_manual.pdf