I can't get my tub to drain even after I used an entire bottle of draino. I think that it is the drain stop control that has broken. How do I check it?

I am no fan of putting harsh chemicals down your drainage system. Besides they only seem to work in TV commercials. Remove the chrome overflow plate and pull the assembly out. Is the brass bucket/stopper on the end of the wire? If it is then you have a clear shot at snaking the line from the opening. You will run into the trap about 18" down but work your way around that and you have nothing else in your way. Put out about 12' more and test. Good luck, Tom