Here is a couple pictures and a little I learned about changing out the Thetford Sanicon 700 macerator pump. The macerator pump is located in a small plastic tank between the grey and black water tanks on the 2552. The part numbers are 97518, gets you the tank and pump; 97508 gets you just the pump. I bought the tank and pump because I couldn't just get the pump (sold out). I reused the old tank so I didn't have to mess with installing new piping on the new tank.
To remove the pump you must remove the tank, which means ensure your holding tanks are empty.
1) I removed the tank by disconnecting the piping from the tanks at the tank discharge valves (removed the 4 bolts and nuts at each valve)and let the Auto Drain valve actuators hang by the wires.
2) Cut the 4 wires going to the pump, and then removed the long piece of bar stock that was zip screwed across the blackwater piping attached to the frame and hitch. NOTE: this piece of metal was wearing through the blackwater piping, (added rubber between metal and black water piping to prevent further chafing during assembly).
3) Then the tank could be removed.
4) I then removed the cover, 8 Philips screws and opened it up.
5) The pump is under the cover and is mounted with 4 Phillip screws. The discharge slides into a pocket and is sealed by a O-ring. The wires are sealed by a rubber sleeve with a gromet on the end.
6) Pull the pump out of the tank.
7) I simply reversed the process to install the tank, the only issue I had was getting the valves aligned back into position. I ended up getting the sealing ring for the black water valve out of position when I bolted it in. I should have operated the valve by hand, but used the Auto Drain valve actuator and it ended up breaking the gear box inside the actuator (currently on order)
8) Wired the pump back up. The pump has an internal overload, so it has 4 wires. The Black wire is positive, the white wire is negative and the 2 blue wires are the internal overload. One of the overloads wires are connected in series with the switch to the pump and relay that supplies power to the motor, the other wire is connected with the ground wire of the motor.
I took the opportunity to install new valves and actually use my pressure washer to clean the inside of the holding tanks which came out very clean. I have a variety of ends and fittings that allow me the option to spray at 90 degrees etc with the pressure washer.
I probably should have took more pictures. I have included pictures of the ohm readings of the motor and overload, new and old so if you have issues you can see my readings from old not working to new and working.