We are having problems with our bath tub drain. We have used draino and the like and for a short period it works. However I am looking for a more efficeint fix. I have tried to remove the drain cover before but am unable to do so. I assumed it was attatched to the overflow, but was wrong. The cover is different than most I have seen. If I turn it a 1/4 way, it props up and allows the tub to drain. If I turn it another 1/4 way, it sets back in and covers the drain. How do I remove this sort of design?