Radon mitigation systems are common in our area and I am not sure why that would scare someone off. Many new homes have them installed. As far as your foundation problems are they being disclosed along with the work that was completed/guaranteed/warranted? How much work had to be done? How are you priced as far as comparable properties without the foundation repairs?
I would suggest you sit down with your agent and discuss what is being done to alleviate people being scared off. Is the information being explained properly? Pricing? Feedback from showings, etc..
I hope this helps!
Are you still having challenges selling your home or have you resolved the problem?
I've sold a number of homes in Oak Lawn in the past year. What's your property address?
I would like to look up the listing to give you an idea about whether the problem is actually photos/marketing rather than the radon system.