The only thing I can tell you is you should immediately put the softener on bypass...you really dont want that crap getting into all your valves and faucets throughout the home
I dont know anything about the fleck valves or how they could siphon out the resin.. I see it a lot with Autotrol units...
I dont suppose you could have the thing plumbed backwards, with the in and out in reverse???
As far as bleaching the well, I hope that you bypassed the water softener and flushed out the bleach before letting it pass through the unit???
you ought to e-mail gary directly about the fleck valve