Many moons ago, before I knew any better, I purchased a plug aerator as part of a package deal. Turns out the previous owner had seriously abused the aerator, bending most of the spoons 90-degrees. His yard must have had multiple buried concrete clothesline anchors ...
I finally got around to doing something about this mess. I figured that if I couldn't fix the tines, certainly there would be replacement parts available. Right? Uhm, no. I can buy the larger 3/4" plugger tines for the Bluebird commercial aerators, but the smaller 1/2" tubular types appear to be made of pure hensteethium. Precision and Agri-Fab have long since moved to a flat plugger tine that is incompatible with this model.
So I took the thing apart, and set to straightening the bent tines. A simple piece of steel tube made quick work of the slightly-bent spoons, but the 90-degree victims needed more care lest they tear in half. I found that squeezing the bend in my big bench vise would open the tine without tearing the metal (too much,) then I could roll the piece on my steel tube/mandrel while expressing my displeasure with the ball pein hammer. In all but three cases, I was able to straighten the spoons without catastrophic separation.
I spent about two hours welding the tears closed, and running a bead over the tang the manufacturer used for the initial bending operation. The tang hole creates a fundamental weakness in the spoon, and all were bent at this location. The three separated tines were seamed back together. Two remaining tines were sans-spoon. I fabbed replacement ends from some tube stock on hand - yes, it is EMT, which ain't the best choice for this. Each spoon received a weld up each side to prevent re-bending, along with whatever welding was necessary to close-up the metal.
Everything went back together, and I took it for a spin around the new garden. There are large clumps of soil and turf still floating about, and the aerator did a decent job of breaking up the lumpy bits. I bashed about the garden for a half-hour, and none of the spoons failed. I may have to keep this appliance in it's current form. It certainly has a more menacing look with all the spoons straightened out.