The white nylon wear washers that keep the diaphragm retaining washers from chaffing the diaphragm are a little tricky. The inner is easy as the plastic pins keep it in place. But the outer one a person needs to keep it manually centered while installing the retaining nut or it will fall down out of place. This is even a problem at the factory because I have rebuilt ones where the washer had fallen out of place during factory installation. It is not hard, just takes some attention to detail.
When installing the flapper valves, diagonal cutting pliers can clip the retaining tab off to get the old ones out and also to clip the excess installation portion off after installation. Take care to put them in the right direction. The valve side goes on the cupped side of the valve body. They pull through a little easier if you spit on the tab first.
The diaphragms are a little tricky to get stretched into place. Have to remove the nylon retaining ring to get the old one out of the body, finesse the new diaphragm into place and replace the retaining ring.
It is not necessary to remove the cover off the motor to rebuild the diaphragm assemblies. But I have found it to be easier in that you can reach in and force the armature toward you to make it easier to get the parts assembled to the motor shaft. Otherwise the motor shaft tends to want to go away from you making it hard to get the parts and retaining nut on the shaft easily.
Clean the intake filter. In the kit they give a new seal for the air box but there is rarely a need to take the air box apart. It can get some debris in it from a failed diaphragm but I see no need to take it apart. I did once just to make sure that was not a source of an air leak, but it was not needed. There is also some filter material in there just to keep rubber pieces from exiting the outlet in case of a diaphragm failure.
They put some odd pieces in the rebuild kit. They put a new seal for the air box, but the air box rarely ever needs to be taken apart. Yet they do not put some parts that I can see might be needed (but so far after a half dozen rebuilds I never have). For example they give you an air box seal yet do not give you one for the valve manifold which is much smaller and more prone to damage and has to be taken apart when you replace the valves.
All in all I have been happy with these pumps going on 3 years now up until now. Now I have three of them I can not get to pump up to over 3 psi, so will not work with the depths I need. This I am disappointed in. They run fine, they pump air fine, they will just not develop the pressure I need for the depth I have so will not work as intended any longer. And I have no idea why, other than the guess that the motor is weak and not pulling the diaphragms to full stroke. I have checked for leaks in the air box, connecting tube and valve manifold assembly.
I was asking a lot from these pumps and they have preformed adequately up till now. But I think it is time to move on to a more robust pump. The diaphragms last about 6 to 12 months of 24/7 running in my experience (summer running, no winter temps). Rebuild kits are readily available. They recommend max depth of 11.5 feet but I would recommend no more than 8 feet. Air flow drops off rapidly with depth due to the nature of the linear actuated rubber diaphragm pump design.
