You can make a perfectly effective thread cleaner out of an old bolt. Take a bottle cage bolt with longish thread and make two cuts along the length of the threaded shank using a junior hacksaw or file them using a needle file. Make the cut deeper at the leading end of the bolt shank and shallower toward the bolt head. Remove any burs with a little wire brush if you have one. It's basically a homemade tap, you can't use it to cut new threads but it will repair bruised threads and clean out any muck. You can reuse the same 'tool' for years. Here's a sample pic i found online but i suggest making the cuts deeper and longer than this photo.