I inherited a rented apartment with a trip-lever drain stopper in the bathtub with the stopper itself missing (see attached images). The maintenance told me that they cannot replace the missing part and gave a generic rubber cover instead, which is both inconvenient and hideous.
Ignoring the fact that this apartment is some 60 years old and the entire thing is in pretty bad condition, what would I need to know to order a replacement myself? Presumably, installing it would be as simple as sticking it in the sinkhole once I have it.
I can see that the lever handle was made by Kohler, but I am unable to find any similar-looking products on their website and their customer support told me that I have to replace the entire bathtub which seems a bit excessive. I am worried about ordering a plug from a different manufacturer as I have no way of knowing if it is going to be compatible (although presumably the only thing that matters is the diameter, but I am not sure).
I was hoping to get some advice on finding a suitable replacement for the missing component that I can buy and install myself without getting Kohler to replace the entire unit.
Unfortunately, I know absolutely nothing about plumbing and have never had an issue like this before.