here you go.
J1 com2 seems to run to heat pump
J2 com1 runs to the Screen Logic switch up in the attic
J3 com3 runs to SWG on J20 on main board
i also included pic of control panel showing lights and laminars on their switches
You said your ScreenLogic has not worked for years. I would disconnect the SL form J2 in case it is interfering with the Intellichlor.
Then I would move the SWG from J2 to J3 to see if it gets things working.
salinity is around 3500 using both a lamotte digital probe and and taylor salinty test kit. they are within 100-200 of each other
JamesW is trying to see what the SWG thinks the salinity is. You know the actual salinity you measure. We need to see what is displayed to have an idea what the cell is calculating the salinity to be.