As we already can perceive there are irregularities in the forms of the 'balls' / 'rhombs'. The sizes also varies (even in the same glyph). All these different designs presumably are intended to give more information than what follows from the fundamental concepts of the two main variants. For example, Ab6-63 and Ab6-65 surely are intentionally drawn differently:

Similarly, Ab5-67 and Ab5-68 are surely drawn not to be alike:

A single 'ball' only appears as head in GD56 (Aa4-28) and in GD15 (Ab2-4, Ab2-60):

Immediately to the right of Ab2-4 we find a glyph (Ab2-5) with two 'balls' (seen only as semicircles) appended to the uplifted arm:

This construction is used in other glyphs too, Aa4-7, Aa7-11, Aa7-27, Aa7-49, Ab1-4, Ab1-54, Ab1-66; 8 glyphs in all:

Possibly there is a similar construction with a 'rhomb' in Aa4-1, just 6 glyphs before Aa4-7:

That only half the 'balls' sometimes are used is clear from Aa7-24:

Marks appear on the left side in Ab7-75--76 and Aa2-53--54:

Also 'rhombs' may have marks of a similar kind, as seen in Aa5-8, here compared with Aa3-39:

The little 'eyes' are seen in other glyphs of the 'rhomb' variant too, Aa6-82 and Ab7-62:

A single mark at the top is seen in these glyphs, Ab5-52, Ab5-55 and Ab5-58:

From this observation it becomes evident that also the 'ball' variant may have a single mark of this kind, Ab7-32 and Ab7-36:

In the strange glyph Aa2-9 a single 'ball' maybe is presented, with the vertical straight line extended into a kind of vertical bar:

Furthermore, a vertical bar (GD37) - with three slightly different forms - appears in Aa7-55, Aa7-66 and Aa7-74:

In Aa6-47 a single 'ball' appears as an elbow ornament:

Exceptional are Ab8-74 and Aa8-80 (both close to the end of respective tablet side):

A single 'half-ball' possibly is meant to be seen in form of the ear in Aa2-26 (GD56), on top of the head in Aa7-8 (GD15) and at the back of the head in Aa7-11 (GD15). A single 'half-ball' may also be seen at the thumb in Ab8-58 (GD56) and a 'half-rhomb' possibly appears at top left in Aa2-45 (GD36):

It is not always easy to perceive the difference between a 'half-ball' and a 'half-rhomb'. The vertical straight line is of help, but cannot be totally relied upon, as is seen in e.g. Ya2-101:

After hesitation I have included Aa2-67 as an example of GD53:

I have included a hyperlink to GD44 because I suspect that we there have glyphs with half a 'rhomb', like in Ab4-10:

Similarly I have inserted a link to GD55 because there we have glyphs which show half 'balls', e.g. as seen in Aa7-7:

Of course, there may be other glyph types where one 'ball' or 'rhomb' appears as the 'head' or otherwise, as in e.g. Aa2-14 (GD78) and Aa7-31 (GD113):

But it would be impractical trying here to define which such glyphs incorporate GD53.