Repair a bicycle lock

About half a year ago, I bought myself and my wife two bicycle locks. As a set they were cheaper together, but still cost me about 70. After a short time, the plastic wrapping between the metal started retracting. My last lock had a similar problem, leading to rust which, two years later broke the lock. This isn't exactly the security you expect from a good lock. But, thankfully, just a little bit of sugru helped to seal the gap! Andreas