Why do hand held can openers stop working so quickly? Is there any way to fix or adjust a hand held can opener?  I keep buying new ones because
within a month or so of buying them, they won't roll correctly on the can lip.
Can openers do break. 

But if they're breaking quickly, then I'd suggest you're buying very cheap can openers. 

One of these should cost $10-20 and should last at least a year.