Based on the chlorinator I sold and mialynette's statements concerning the length of time between his servicing his customers that are using it, yes, he is not servicing it per the manufacturer's instructions.
You have a problem with blocked "ports", I didn't and my customers didn't.
The reason I and my customers didn't have the problem was because we cleaned the center tube, the cap and the rest of the chlorinator sooner than your 4-8 moths.
Now IMO, and I suspect the opinion of many the unknowns reading this thread, I'd think you'd see the cause of your problem as incorrect service on your equipment but, all I see and hear from you is that the equipment is bad.... DUH!!
The reality is that it really doesn't matter what the blockage material is, YOU aren't cleaning the ports soon enough to prevent the blockage from forming but...
Without testing the material causing the blockage you make a guess that it is calcium. If you mean hardness scale, in cold water water hardness scale usually needs a fairly good flow through a flow restriction before it can be formed and block the restriction. I suspect you don't know that.
If you don't mean hardness scale, although you did mention the water hardness as a cause, what do you mean by claiming it is calcium; where does it come from? IMO it can only be hardness scale or from the pellets. Or, how about sulfates or chlorides?
IMO you sold equipment without knowing much if anything about it. When you had a problem with it you bad mouthed the equipment and now me because I sold it.
It sounds to me as if you haven't sold many solution feeder systems or you'd know more about their service needs. Replacing solution once a week or once a month is service IMO. Do you have those customers check the strength of their solution after they add solution? How about periodic testing for the chlorine residual? How about blowing down their retention tank? How about follow up water quality tests for whatever they are using the chorine to treat, you let them go over two years for all those things huh...