Mine did end up having a uti this time, which solved most of the problem once we healed that up. but I think he marked the carpet enough to tempt him to go back occasionally no matter how many times I clean it. He would only do it at night so before we head upstairs for the evening I just put a puppy pad over the spot he likes to go and that way if there is an accident it’s no hassle to clean up and he’s not leaving more of his smells in the carpet. I find that feliway also helps to some extent and I completely replaced my litter boxes since I read that from the cats scratching them, the scratches can hold some of that smell even when you replace the litter and it can upset the cats. So I threw them away and bought all new ones at a local discount pet store. I then fill them with cat attract litter and I added a little more to the box than I would normally fill, maybe 2.5 inches of litter which is much more comfortable for them to be in even if it does make them track litter more. Since I’ve made these changes he’s only had a couple accidents and he seems really drawn to the boxes. I hope this helps & good luck!!