How does central vacuum suction compare to regular vacuum?
I'm answering my own question here - maybe and admin can move this as a comment to my original question:

I did some more research on how to detect and clear blockage in central vac system. I disconnected the vac bucket from the unit and then used a regular vacuum at each outlet. At one of them, a huge amount of debris came out, including a "fabric softener" sheet and some other bits of dirt. This must have clogged the system enough to drastically reduce suction.

The change in power is unbelievable.  Certainly more powerful suction now than my regular vacuum.