I found another set of very organized (grid style) ribosomes at the growing end of what is likely a profile of RER which contains the layered protein I think might be surfactant protein A (in over-production).  More data are being gathered. Here is yesterdays video with the second tangential set of a dozen or more ribosomes added.

Since the size of surfactant protein A is about half that of the proposed width of a period (the 3, 5, and 7 sometimes prominent layers that general run parallel to the long axis of the RER cisterna (but not always) it would be really convenient to think that just on either side of the dense band there is a ribosome that is producing the protein.  That would be too tidy for words.