We had used the Manta which we inherited when we bought our house back in 1998. The vacuum has done a great job and has been fairly quick, taking about 1 1/2 hours to clean a 15x25 52" above ground pool. This year, the unit has not been doing so well. The diaphram is still in good condition, it may be related to the house. I'm going to try another hose and if all else failed, will be searching of a replacement vacuum.
I will say, the model we have is from 1997. Since then, I believe Zodiac had bought them out so I am not sure about the newer models