I had a friend who had a Sundance and it leaked like a sive.Come to find out they had a defective glue they were using during that time frame.What a mess that was.He did finally get another spa that was of higher quality.
Spaman, in the mid '90's there was a mandate by the EPA to reduce emissions into the atmosphere that were depleting our upper atmospheric ozone layer. You, may recall when all of the automotive airconditions stopped using freon covered under the same mandate.
I don't know that I would call it "defective glue" but it certainly was a new chemical compound that did not give off the emissions. The propreties of this glue certainly changed and it was different. The cure and life expectancy had changed without manufacturers knowing it.
This affected the counter top laminate industry as well, and a large numer of Hot Tub manufacturers, unfortunately learned of the resulting problems 4 to 5 years after the fact. Many of these problems were either covered while under warranty and many even out of warranty. This is where a "good" dealer made the difference for the customer.
Now, the issues is 8 to 10 years behind us and you can believe me when I tell you that the way spas are plumbed today by ALL manufacturers is different. It is the learning process of the industry and the evolution of the Hot Tub as we know it today.