HELP:  Expensive Lowrance GPS problems

It's a Lowrance LMS-520c

It has the latest software.  The sonar works fine and always has, but the gps won't lock onto satellites now.  The lgc-3000 little hockey puck keeps going bad.  This is the 3rd gps unit that has went bad in a year and a half.  The other two were under warranty and Lowrance replaced them quickly with practically no hassle.  All three times it has done exactly the same thing and as soon as I plug a new lgc-3000 into it, it works perfectly for about 6 months.  I do not get the message GPS NOT RESPONDING.  In fact it doesn't give any message, it just doesn't lock on.  If I go to the status screen and watch it try and lock onto satellites it never finds one.  The status screen actually changes when I have this problem.  When it is working correctly it lists all the satellites along the bottom of the screen with their bars above them showing signal strength for each one.  When the gps module goes bad, the screen changes to only show one satellite at a time.  It no longer lists all the satellites at the same time.  It shows one satellite and the signal strength bar above it for about 5-10 sec and then the satellite changes to a different one.  All the satellites are always 0% strength.  I know the problem is with the gps module because of how many times it has happened to me but I thought maybe one of you might know why.  I'm not going to spend $200 on another gps module and it only last for 6 months.

The fishfinder is mounted at the console and the gps module is also mounted at the console about 1 foot away.  I know a lot of people say that you shouldn't mount them within 3 feet of the unit or they won't lock on properly but I've never had any problems locking onto satellites when the thing is working.  My Lowrance book that came with it didn't say anything about a 3 feet mounting distance but I'm still wondering if that has something to do with it.  Has anyone ever heard that mounting the gps module to close to the unit can somehow damage the gps module.  I have both the head unit and the gps unit wired into one of my trolling batteries.  The head unit and the gps unit are wired through individual toggle switches and both are running through the fuses that came with each.  After the first one went bad I thought that somehow the onboard charger had fried it by possibly leaving the gps switch on.  I don't know this, it is just a thought, but since then I have been positive to make sure the switches were off before charging the trolling batteries and I would think the fuses that came with it should also protect this.

Anyone have any ideas?

I had a similar problem where it would get the signal but then it was lost. Went through about 2 pucks. Each time we'd get a new one it seemed like the problem was solved. Then they decided to switch the unit. Turned out it was actually the unit itself. It was a 332c. About 2 weeks after the dealer switched it out for us we got a call saying the gps part of the fishfinder was bad and caused the problems.

O and mine is installed in the dash with the puck at most 2ft away. Thats how our dealer does them.

Lowrance recommends that the puck be at least three feet from the unit.