Volvo c30. Cracking after covering and disc change back rarely and only with floor waves.

Hi guys, wanted to spare you, but my learned screwdriver colleagues are already sleeping here. Go around a Volvo c30 1.0 125ps from 2007. Got new documents and discs in the back. (Yes, I confess I did this because I have experience and a learned mechanic friend is always there) Now I noticed that only back right after cracking rustling occurs. But not always, and only with floor waves. Of course I researched and found out that manc I have to say it’s NK pads, where the manufacturer guarantees 3 years of fit and it only happens to the right. Then I found a thread where someone solved the problem by replacing the brake springs outside because the too much game ergo was sucked out. Now my question before I get new brake springs, even if that’s only penny parts costs. Or it’s still my question before I get new brake springs, even if that’s only penny parts costs. which is more expensive. I thought to test the brake so to speak. I took a long screwdriver (flat). I used a lever from the steel rim a hole and tried with the screwdriver to push the brake force (brake caliper) away from the brake disc. But naturally without violence and light. If I did this on the left does nothing. If I did this on the right, one heard a slight cracking. Could the spring be to blame? After all, the first ones are still the first ones. in and see year of construction. Thank you in advance.