Here is an update on this in case anyone ever runs into this same issue. I was able to get in touch with a tech rep who works for Blaw-Knox and at least find out what these are. The part number for them is 12832551 and they are simply called out as plugs. You are able to order them via a dealer from Blaw-Knox. He said typically he usually sees them on Ultimat 8/16 and 10/20 screeds, but our machines have an Omni 1A and Omni IIIE screed. It seems where the confusion started with our pavers is that they are IR pavers. The manuals we have came with everything about the paver and its controls, but all the screed manuals were listed on the front cover as "competitive" and not included. I'm not sure what the story is there, but apparently we need to order some more service lit.