Yes I can give you an answer....
My parents met one another when they were both working in a vacuum cleaner factory in the 1930s.
I grew up in the 1940s and 50s watching my father repair vacuum cleaners on the kitchen table - at his knee.
Later on after an apprenticeship as an instrument & electronics engineer I found it no trouble at all to copy my father and repair vacuum cleaners for myself, my family and friends.
In this time I might have repaired about 20-30 vacuum cleaners and have never had to change an on/off switch - I do not recall my father changing one either.
Now - if your machine is not working it may well be down to a defective on/off switch - but based on my limited experience over an extended time the switch in your machine will be working as it should.
A common fault in vacuum cleaners is a broken conductor inside the cable at the plug end - caused by over enthusiastic tugging by the operator. The solution is to cut six inches or so from the power cord at the plug end and throw it away and to fit a new plug. This takes minutes - fixes well over 50% of vacuum cleaner faults and costs virtually nothing. Well worth doing before attempting to mess with the machine's on off switch.
Good luck...
Peccavi
January 2013