This is a sticky part, so its best to have a clear understanding...
First "the manipulation of information" is not specific enough - what do you mean by 'manipulation'?
Function of the episodic buffer: on instruction from the central executive, retrieves information from long-term memory, before recommitting the modified memory back into LTM.
The central executive: receives and processes information from the phonological loop, visuospatial sketchpad (i.e. the storage components) and episodic buffer, as well as from LTM through link of the episodic buffer.
It has 3 main functions:
* directs attention
* responsible for shifts of attention
* modifying answers brought in from LTM, before recommitting them back to LTM, through link of episodic buffer.
It is also involved in decision making (i.e. decides what to do with the info its receives from the two storage components)
Hence, manipulation of information to solve problem is combination of these two components of working memory.