Gear problems and causes / solutions

I came up with the idea of starting this topic as a useful resource for finding out what problems people have had with equipment, and what the cause was, also what solutions they used to rectify the problem.
The idea came about after reading the topic "What's wrong with my Thermarest and can I fix it??"
I'm making this topic a "Sticky" in the hope it builds as a useful resource, so topic related posts only please.
The Thermarest problem -
It can be blown up hard and it will hold air almost forever but when slept on the thing deflates and lets the person contact the ground. Put in the bath and can detect no bubbles coming from the surface.
The thermarest is 15 years old, and has patches.
The solution -
As suggested by a member, it is brittle hotmelt glue on a patch. The old glue removed and repatched with a chunk of packcloth and roofing silicon.
So far so good.
The idea came about after reading the topic "What's wrong with my Thermarest and can I fix it??"
I'm making this topic a "Sticky" in the hope it builds as a useful resource, so topic related posts only please.
The Thermarest problem -
It can be blown up hard and it will hold air almost forever but when slept on the thing deflates and lets the person contact the ground. Put in the bath and can detect no bubbles coming from the surface.
The thermarest is 15 years old, and has patches.
The solution -
As suggested by a member, it is brittle hotmelt glue on a patch. The old glue removed and repatched with a chunk of packcloth and roofing silicon.
So far so good.