Central vacuum not sucking (by 2 users)

Usually when there is no suction, and the main unit is running, then either the hose or somewhere in the piping there is a clog. If you move the hose to another location, is there suction? If not then the hose is clogged. You can unhook the pipe at the unit, flip the switch to manual, if it comes on and there is suction there, then there is a clog in the piping, If in the piping, tear up small strips of paper and mark them by number and insert one in each inlet, run the unit on manual to suck them up, and which ever numbered strip isn't there in the bucket, then that is the inlet that is clogged.