As best I can tell from the pix I have seen of the Beaver Blades, you do not tighten them. The chain does not run around the blade but appear to be permanently attached to the blade via fasteners. I imagine the chain(s) will just move a little more if they loosen up.

I also imagine you just sharpen and lower rakers (assuming it has rakers) as needed just like chainsaw chain. My guess is that the chain sections are not meant to be replaced and you would buy a new blade.

I have used a beaver blade for a number of years. I have always had great results with it. It does get dull, just like any chainsaw would. I have sharpened it with a file and also with a chainsaw grinder (you have to be very careful when doing this). Safety equipment is highly recommended.

I own a sharpening shop. I finally wore out the chain. I decided to see if I could replace the chain. It worked. I broke the chain with a chain breaker. Then I removed the chain and counted the drive links. It was a .325/.050 chain. I then cut a piece of chain with the same number of drive links, gently tapped in into the two disks of the blade making sure there was no slack, and then put in a master link like you would with any saw chain. I now know the chain can be replaced economically and I can do this from now on. Hope this info helps you out.