Thomas, let's see what your Table tells us.
Your scale has 19 active items. 63% of the variance is unexplained. This suggests that the item difficulties and person abilities are central. In fact, the items (22%) are more dispersed than the person (15%). This may be good or it may be bad.
For instance, for nurses at the end of their training, we expect them to have very similar competencies. We want to see very littlle dispersion in the nurse ability estimates. So, if the study skills of your sample are good, we are happy to see that there is little dispersion of the skill "abilities".
The eigenvalue of the 1st contrast is 2.7. This suggests that there is a secondary artifact with the strength of about 3 items (out of 19) in your scale. Is this a dimension or an accident or what? To investigate, we need to look at the content of the items.
Your Table 23.2 has an interesting vertical distribution in its Figure. We can see that items A,B,C are off on their own. Which items are they? Table 23.3 tells us ss9, ss10, ss5. Now we need the text of those items. (It is easier when the text is summarized in the item labels). What do those items have in common that the other items don't have? If there is something. Then it is a secondary dimension or merely a content strand (like addition vs. subtraction in arithmetic). If there is nothing, then the eignevalue of 2.7 may be an accident.