Butterfly knives (Balisong), Automatic knives and any spring assisted knives including gravity knives are classed as a prohibited weapons in Canada, and pretty much everywhere else.
Possession, manufacture, sales, repairs, handling and transfer (shipping) are subject to a Canadian Criminal Law.
It is against the law to carry or repair such knives since 1957 in most states in the USA.
Therefore most companies that could repair such knives do not.
The law treats switchblades as contraband, and made it illegal to transport automatic knives across state lines.
You may be able to find an individual in the USA that can and will repair your knife, but do not count on it.
Any such prohibited knives can, and will be confiscated by Customs if shipped cross borders, and the shipper can be fined and prosecuted to the boot.