Doug,
That's not exactly true. Slots in Canada are to be returned to the US where they are then re-sold. Ownership of any sort of slot machine is still, unfortunately, a federal crime in Canada although they turn a complete blind eye to it unless they are cracking down on a basement gambling operation. The other unfortunate thing about the law is that if you SELL a slot machine to someone one and then THEY commit a crime, you, the seller, can also be on the hook for it.
Now a lot of people have access to Japanese slot machines called "Pachislo" and they are an entirely different beast altogether (and exceedingly difficult to repair without some connections to the Pachislo importers).
Parts for purely mechanical antique slot machines are available in the US as there is quite the collector base.
Slot machines in the early SS era are difficult to diagnose and repair as they usually have to be re-capped. Parts are near impossible to find in Canada unless you can scrap machines. Later SS and newer machines are a little easier to repair and you need to connect with the Slot Technician community online to find collectors and repair guys who will burn roms and security chips for you. Most of the slot machines do have available instruction manuals, sometimes schematics (but usually not as much the later as repairs eventually became proprietary card swaps). One of the problems with repairing the middle and later SS machines are the proprietary security chips that are needed to make the machines work. The other issue is the type of coin they accept (and CDN bill acceptors can be quite expensive). Bally won't talk to you unless you are a casino tech, but they used to allow outsiders in to their resources for a while.
Sometimes all that is necessary is to find the right slot manual and then re-establish the security sequence with the right keys to reset a machine so that it isn't locked up.
But repairs are not impossible. You just need to search the web for "slot techs" and one of the best places to start is here:
http://www.slottechforum.com