VINYL Liner Connection Separation

[melbajr]

I really don't know how to explain this so I've posted a photo.
The top of the liner is supposed to stay behind the track above it. Here you can see an approx. 4 inch section that has slipped out of its track.
If I press it, it will go near to where it should be but not stay. It's really difficult to press like there is extra wall foam behind it. But I don't really know.
This is the only spot I've seen like this.
How worried should I be? Can I fill the split with silicone (it's less than 1/8") but I know silicone won't keep it from spreading if that's what's going on. Or should I call the installer? The liner was replaced 4 years ago when we bought the house.

 

[JVTrain]

It could be that the liner track below the coping has sagged in that area or the bead on the liner has flattened/stretched. You could try installing a small section of liner lock. Quaker Plastics Pool Liner Lock (120 PER BAG) - QP1562 - INYOPools.com
You may be able to buy a smaller piece from a pool store since most I've seen online are 120' rolls... much more than you need unless you plan on doing the whole pool.

I would not use silicone as it won't provide a good physical hold on the liner and will be a hassle to remove.

 

[Davejavu]

Quick tip: Moving with your liner is pretty difficult. You can adjust it much easier by pouring nearly boiling water on the liner. It really takes the stiffness out. BTW, this tip was from the liner manufacturer when they hand delivered our liner to us after they mis-cut our first liner (so it should be safe to do).