Delamination of your valves
When your valves are delaminating, this means that your buddy is asking for retirement. Most kites produced before 2010 used a thermal sensitive glue to make a strong bond between the base of your valve and your bladder.
Due to the thermal sensitive glue, high temperatures and time cause delaminating of your valves.
What to do?
You can't do anything about it, other than replacing your valves. If one valve starts to delaminate, others will follow on short notice, so replacing bladders is the only option. If the canopy is in no good condition, don't spend any money on replacing just one valve, just be brave and let it go...