Just a few checks you can try if not already. The answers will also help the experts trouble shoot your issue quicker.
I'm guessing your Free Chlorine is dropping or not increasing?
Can you see the cloud of chlorine inside the cell while it's on?
Have you tested the water out of the return and compared it with a sample from the pool away from the return? The FC should be higher if the cell is working.
Do you have a Multimeter to measure the Volts and current going to the cell?
Do you have current test results from your CCL kit?
At least your plates are still there. After I bought my place I found all but two plates had fallen off. Some were in the cell housing and the others were on the ground around filter.
Did you have any luck finding a service manual?