Aquaponics : replacing diaphragms in aerator

Last year I lost some fish when an aerator failed.  I replaced the whole thing but since have learnt that it is possible to replace the part that fails in them called a diaphragm.
So yesterday I purchased the required parts and proceeded to pull an aerator to bits to have a go at replacing them. 
The aerator  I use in my systems is a brand called "Aqua One"- they have a 4 tube outlet and  I have generally been satisfied with them.  However  after 12 months of constant use the rubber diaphragms develop small tears and the amount of air pumped through the tubes into the water obviously declines or ceases
 The first step was removing 6 screws from the base  -this opened it up where the bits to be replaced became obvious.  Each arm was unclipped to access a small screw/nut holding the rubber diaphragm to it. There are four diaphragms to be replaced in the model I have.

After replacing each diaphragm reassembly was also straightforward.

After checking that it all works ok ,  I have written a date on the side so I remember when I replaced the diaphragms