importing rules

Is there a way to import rules from my old Mac backup onto my new Mac if I failed to export my rules from Hazel before getting rid of the old machine?

You can find your rules in your Library/Application Support/Hazel folder. It's all the files with the .hazelrules extension. The problem is that they are not named in a way that is obvious. You'll have to import the file to see what rules they are then move the rules to the correct folder.