Owners are to blame for 99% of problems
They didn't follow directions--especially wiring it--when installing it...or in an effort to conserve power, they flush solids and/or TP without running it, which clogs it. Or they flush things that shouldn't even go down the toilet, much less into a L/S. But the most common problem, especially in warm waters, is failure to clean it as called for in the manual. Sea water calcium carbonates build up on the electrodes, essentially "insulating" them, which prevents 'em from creating any chlorine...and which causes the "low salt" light to blink. Instead of reading the manual to find out why, owners just dump more and more salt in, which does no good...the discharge starts to stink...they have a yard who's just as clueless as they are check it...they decide it needs new electrodes (expensive!)...which does indeed fix it...till the buildup occurs again. But all they really needed to was clean it, which doesn't even require taking it apart...just a solution of muriatic acid in it through the toilet according to the directions in the manual...about every 3 months in warm waters (i.e. FL), once a year or even less often in cooler waters.Install, operate and maintain according to directions and a Lectra/San will give you literally decades of trouble-free service.