916 Spider roof sagging
I've got a 2001 916 spider, it's in really good nick and I've spent loads of time and money keeping it that way. Just lately though, I've noticed that the roof if beginning to sag (very slightly) at the front in the middle. I've regularly waterproofed and treated the hood with Renevo ultraproofer (which is great BTW) and I don't know what else I can do to try to improve things or stop it from getting any worse.
Has anyone seen this before and got any solutions they can suggest?