Put the summary of the bug you're having here

What I expected to happen was...:
The item pipe which extract items from centrifuge to item chest all the time

What actually happened was...:
The white box which is the opening extracting point made by cable wrench become no more after the items in centrifuge is cleared out and new items processed by centrifuge will not extract to the item chest. This means that I need to use cable wrench every time the white box is gone. 

Steps to Reproduce:
1.  Item processed in the centrifuge and used item pipe to connect centrifuge to a item chest
2.  Cable wrench is used at the starting point so that the processed items in centrifuge can flow to item chest. 
3. After the processed items in centrifuge are cleared out, the starting point is gone.  Cable wrench is used again for the same starting point spot and the point is gone after item cleared out.