I really love the Dewalt 735 Planer I've had for several years now. I think it's one of the best "portable" planers out there, but its stock, highspeed steel knives can wear out quickly. Plus, it can get pretty loud when running through hardwoods, so it could really use an upgrade.
Some of the newer models come with helical cutterheads with carbide knife inserts, but if you have an older model like mine, you can also find replacement helical cutterheads, as well. With a new cutterhead, you'll find that your planer will run quieter and give you better results.
I got my new cutterhead from FindBuyTool.com, and in this video, I'm going to walk through the process of replacing the cutterhead in my planer.