You're a bit vague on the problem you have - probably a loss of suction.
If you cover the hose connection hole with the flat of your hand you should be able to feel the suction - the machine will run faster with no air to shift. This will tell you that there's a problem with the hose - if the hose was blocked and you connected it then the machine will (should) run faster as if you'd covered up the hole.
If the machine just runs at normal speed with the hose connected and there's poor suction then air is getting into the machine some other way - probably through a split in the hose.
If you prevent air entering the machine for too long there will be nothing to cool the motor - it will overheat and the safety cut-out switch will operate - sometimes a dirty internal filter might cause overheating.
Good luck...
Peccavi
May 2013