My first vro lasted 12 years replaced 18 months ago . The new one is now bad took both apart and the air pump diaphram is bad in both. The rubber coating on the back side of neoprene is cracking but the rubber is still flexible and soft.What can be causing this? I do not want to destroy the new one. The boat hasn't backfired, I replaced the pulse limiter on the last one as well. Can it be from engine tuner or alcohol in fuel!