The base was gravel that had been in place for about 15 years with no real problems in spite of the grade, everyone i have spoken with has said that should have been an ideal base
Right now I'm leaning towards the guy that was out today. has 31 years exp and believes it just water getting under it from all the joints etc. Even though they are all caulked he pointed out several are no longer sealed.
He wants to re-caulk the entire thing with an 8 year non pro rated warranty. ~ 4.5K works out to about 45.00 a month which is a lot less than I have been paying on an annual / semi annual basis. he works for the owner and has been in business for 10 years. have to do a bit more research but the warranty is appealing in spite of the cost
Thanks again to t hose that are responding