Had a plumber come and cleanout cellar drains. When he removed cleanout he found it was just stuck into pipe (metal). Why? While the cap had threads on it, there were no threads on the T into which is screwed into. When he was done he just pushed it back in as far as he could, then wrapped electricians tape all around it. I'm not crazy about that at all, as twice in the past 2 years the local storm sewers backed up and if did so again, water may push this plug out. How can I put in a watertight plug, cap since there are no threads left on the T. I found some Fernco rubber caps but they come in 1.5" , 2" and 3 ". The hole is 1.5" but with the hub/collar I need something bigger to slip over it, the 2" was a tad too small, the 3" way too big...help!!!