Hey there! It's happened to me before, and it can be such a pain! One thing I tried was using some silicone grease or lubricant on the threads to make them smoother, which seemed to help a bit. And if you're up for it, you could also look into getting replacement screws from hardware stores or online shops. I've found some good options at places like Scrooz (https://www.scrooz.com.au/), which has a variety of screws and fasteners. Anyway, I hope that helps you out with your radiator. Sometimes it can be difficult to solve the problem without the help of professionals.