FYI - While the drum sander is down, I took the opportunity to upgrade the dust collection for the drum sander. I replaced the 2.5" splitter and 2.5" hose that goes to the drum sander and the spindle sander with a 4" splitter and 4" hose. I also added a blast gate dedicated to the drum sander and one dedicated to the spindle sander. I recently revamped my home shop dust collection ducting and had some left over splitters and blast gates.
The prior dust collection setup did not have dedicated blast gates for each sander so the air flow was split between the two sanders. The increased hose size and being able to focus all the air flow to one of the sanders as a time, dramatically increases air flow. Unfortunately my hand held aerometer broke so I could not measure the difference at the top of the drum sander. The new set up really sucks (in a good way), feels like a 4x to 6x increase in airflow.