I have owned two Henry's for quite some time, a .22 mag Golden Boy and a .22 lr, both lever actions. Most of the time, all you need to do is clean the barrel just like you would any other rifle and then clean the bolt face, chamber area, and extractor with Q-tips that have been soaked in Hoppe's no.9, followed by dry Q-tips. Make sure you do it in that order, as cleaning the bolt first will cause you to have to clean it again once the barrel has been cleaned due to having to clean the barrel from the muzzle end. Since the barrel must be cleaned this way, I recommend a one-piece cleaning rod so that you won't damage the muzzle crown while cleaning the barrel. After all that is done, I pull the lever all the way down and then wipe off the back of the exposed bolt and rub a little oil on it. I suggest performing the above after every couple hundred rounds or so.
Also, and this doesn't need to be done very often at all unless the gun or ammo gets wet, but every once in a while, run a patch with a very light coat of oil on it down the magazine tube and rub in a couple of oil drops on the magazine tube assy (brass tube with internal spring). I learned this the hard way one time after I must have inserted a wet round. The magazine assy was almost rusted to the magazine tube itself.
A few years after the warranty expired on my Golden Boy, the damn firing pin broke. I had fired several thousand rounds through it and decided to completely dis-assemble the gun and try to order a replacement pin myself and install it. Once the gun was dis-assembled, I was surprised at how remarkably clean it was inside, which is probably why they (the company) tell you that dis-assembly is not necessary. The only area that was really dirty was the receiver area above and closest to the chamber.
To actually take the gun apart, just remove every screw on the receiver and on the tang. The lever and trigger assy will slide out of the bottom and after that is removed, you can pull the bolt out of the back of the receiver.
These guns are remarkably well made with the only flaw, I see, being the firing pin. It's made out of a flat piece of steel that drops into the top of the bolt with a very flimsy looking nipple that extends off of the rest of the pin through the bolt.
As far as fixing the gun yourself, you can't order replacement parts besides magazine tubes, loop levers, etc. I had to send the gun back to the factory after first placing a call to them. Everyone at Henry is family and they are very friendly. I sent my gun out and had it back in 6 days fully repaired at no charge, even though the warranty had expired years ago.
Hope this helps! If you have any other questions, feel free to PM me!
Motown out
ARMY1