We hear of this problem before, the problem only happens if your PDF viewer is not 100% compatible with Adobe PDF viewer. For instance the online Google Drive/Document PDF viewer is not 100% compatible and therefore you cannot see some of the pictures.
If you download the PDF file, and open it with the original Adobe PDF viewer you can see full content of the document. You can download the official Adobe PDF Reader for free at the Adobe website (get.adobe.com/reader/otherversions/).
We're a motorcycle website, and while we have some experience with some PDF viewers, we obvious cannot enter to deep into PDF software support. That said, we want to express that we use the original Adobe Acrobat software to create all PDF files, and because Adobe Viewer 9 is the most compatible versus file size all our PDF documents are in Adobe PDF release 9.
From experience I can say that most programs that you need to install onto your computer support up-to version 9 of Adobe PDF. Most online PDF viewers support PDF version 8, which in some cases gives problems that you cannot see some details of a PDF 9 document.
Obvious on a MS Windows computer, Android device, Apple Macintosh, or Apple iPhone or iPad the software from Adobe works very good. For Linux users Adobe has stopped providing a PDF viewer, but the standard PDF viewer in most Linux distributions works with the latest Adobe PDF (Release DC, which would probably be 12) files.
The exceptions, some users of our website have over the years contributed several PDF documents. While we try most of them and converted most to be up to standard Adobe PDF release 9, it's possible that a few slipped by (especially on our forum).
So Bob, I surely hope that this answers all your questions...
For some people who cannot download our manuals, while they're resident in Thailand, we recommend that you logout of any Google service. It's possible that some files are officially restricted to Thailand, and if your Google account indicates that you're not Thai related it could give problems. (Sorry for the weird explanation, but that is roughly how it was explained to us.....)