I am having trouble with this attractive se-tenant set of four. Here is an image of the set in an Upper Left plate block.

My question is - what is the "weather balloon" variety on 778 (Northern Light - Position 6) and 779 (Labrador - Position 29)? The only things I see in Position 6 are details a and b in the following image. These are constant (though somewhat variable) on all Position 6 examples I have, and do not appear on any other of my 15 examples. Can anyone provide an image if this does not involve the "weather balloon" variety?

There are similarly constant flaws on 776 (Chief Justice Robinson) in Position 1, as pictured below. White dots in the "1" and "4" of the denomination. I realize these are quite small but I am amazed at how some Unitrade varieties are indeed small, e.g. 693iii and 693 iv from the 1976 RMC issue.

Another similarly constant flaw in 779 (Labrador), Position 7, in the next image. At first I thought this might be the "weather balloon". Then I realized I was looking at the wrong ship and/or the wrong position. A reddish blob following and slightly higher than "LABRADOR".

Should these be listed by as varieties by Unitrade? They are certainly no smaller than many listed varieties on other stamps. I certainly hope that Unitrade is not going to go the way of, for example, the Australian Commonwealth Specialists' Catalogue which, by and large, only lists the grossest of otherwise documented varieties.
So, a busy little plate block.
And finally as a reminder, if someone could post a picture of the weather balloon variety, I would be most grateful.