Henry does sell parts for the AR7 to the public. They will sell you any part except for the receiver. I ordered several AR7 parts from them for the one I bought used several years ago, and I received quick, friendly service from them. Their website used to list the parts but now it's are only showing extra magazines for the AR7.
You can download the
manual, and use the part numbers (w/prices) in it to contact Henry at 201-858-4400. Kathy Scarpa is their customer service rep. for parts and repairs.