Water leaking out from behind the hot and cold handles of my shower has evolved into a steady stream of water. Any suggestions? I removed the stems and the washers appear intact. I was going to repalce them anyway but seem to have a hard time finding exact replacements. Also put on some packing thread which abated the problem temporarily. Any advice would be appreciated - keep in mind I'm not a pro (or even particularly handy) so detailed advice would be best. Thank you.