Pentair 320 Chlorinator Troubleshoot and Repair - Hi Flow Feeder Kit Install

Have a Pentair 320 In-line Chlorinator. The Pool has always suffered from low chlorine. I replaceed every part, read all Pentair manuals, followed all the self-help online I could find, and even paid 2-3 pool service companies to look at this. All told me I needed to "upgrade" to Salt, 300 Off-line, et et of course for $$$ mucho dinero. So I tried looking at this from a basic physics perspective, and saved myself thousands of dollars and expensive shock treatments. Hope you can too!