My antenna recently bit the dust, too.  At first, it was an intermittent problem, so when I sent the unit in to Lowrance in Ontario (Rauer has retired and there's no-one in Vancouver who's up to speed on the units yet), they could find nothing wrong.  It seemed the more effort I put into trying to solve the problem, the longer the unit would function before expiring 

.  I finally isolated the problem by switching the components around with a buddy's who has thwe same unit.  Anyway, Lawren, the customer service guy at Lowrance, sent a new antenna and cable free of charge (my unit is 4 years old and well out of warranty)  I spoke with him on a Wednesday at noon and the UPS truck pulled up in front of the house at 10 AM the next day.  He even included a free shipping label to return the defective antenna.  Great service!!!
He also spent at least 1/2 an hour answering a number of questions that had been stumping me over the years.  A real bonus to be able to have the unit working in front of you while you ask the questions.
Mine is the 330c DF, an even earlier model, and I have loved it since the day I got it.  Based on my experience, I'll go Lowrance from now on.