Lift and Turn Tub Drain

So I have a slow shower drain. I went to go clean out the "trap" which may or may not exist. The set screw that holds the drain top in place was heavily corroded. So now the set screw is stripped and there is no way to get the top off that I can see. Any help would be greatly appreciated.

drain

WE dannot "see" it either. How about a picture of what type drain you have. The "trap" is not usually cleaned from that location.

drain

The best way to fix that type of drain is to drill the screw out, then remove the entire plug assembly from the bottom of the tub. Then purchase a new push/pull assembly and install it.