We've checked the laterals and pipe from laterals up and all fine , spider gasket fine , but sand keeps going in pool and into the multi port any help as I've taken it apart 4 times and just cannot see a problem, we have the intex 1200mpg and 16 x48 above ground pool sand is 0.4-0.8 mm silika , every time we re assemble it does it again meaning a complete strip down of the mutiport inc removing handle to remove the sand