Not a schefflera but a Pachira (aka Money Tree, Good Luck Tree, Umbrella Tree). This is a plant that is apparently somewhat difficult to grow, considering all the comments about it in the House Plant Forum.

Can't help you with the yellowing leaves, as this seems to be typical behavior. But I can tell you that your plant has an infestation of scale insects. You need to look for small dark bumps along the stems, even on the leaves. These are the adult scale insects. The sticky stuff is their excrement.

Inspect all of your plants for scale, as the eggs and crawlers are readily spread (usually by us).

Here is a link that might be useful: C'mon....let's see what these folks have to say!