I have an Edwin Jagger DE 89 three piece safety razors and the threads wear out after a year or so of use. The rest of the razor looks shinny and new. EJ has been excellent with their customer service and have replaced them each time. I love the shave they provide and I don't want to give up on them. I also have a replated nickel coated 1930s Gillette open comb new style and the threads have not worn as much, but the coating on the head shows some discoloration. All my other razors are TTO and I do not notice any wear to them. Just a lot of buildup of soap scum and hard water residue that I remove with a toothbrush and some vinegar. I feel I do not treat them harshly. I rinse them after every use and dry them as much as I can. Some of the water can remain in the handle. I have really hard water and I soften it with a water softener. I am wondering if this is causing chrome on the razor threads to corrode and weaken the threads or is there another cause. Any chemist out there that can help with this?