why has my Vax 2400 lost power?

Consider as well - that air might be entering where it should not enter - a poorly fitting case - a split hose.

Consider that dust and grit might have entered the motor area - if so it's a difficult thing to resolve.

Cover the air inlet with your hand if you're able to - sense the suction and listen for the motor going faster with no air entering - off load.

Good Luck...
January 2016

Are ALL the airways clear? Tube, pipes in and around the motor, etc.

XXX
January 2016