The GT is the last model Sovereign that were made, so it is the newest Sovereign and would have though that parts would be no problem for these.
I think the problem we are seeing with a lot of different products is no one is actually can diagnose and repair them, just putting new board in as no one wants to spend the time to see what the actual problem is. Another thing we are seeing is the IC chips have the number ground off so a repairman do not know which IC does what. and I know many companies will not send or post the schematic on them as this will give away the secrets on how they work so competitors can copy them. Now this leaves only the actual Minelab repairmen and designers that work on them as they know what everything does and how they work. Now these guys have to make money like everyone else does and some of these repairs are quick while some take days to trace the problem down, so the repair cost can get really high if you know what I mean. Now they have to warranty them too and if they fix a problem and what cause it does it again then it is back to square one.
What is happening is when like the GT was made Minelab had so many extra circuit boards made that were never put in and these are being used to repair those that the technicians don't want to send the time or cant spend the time figuring out what the problem is, so they just put a new board in and we know that is where most of the cost is as the rest of the detector don't cost that much to make. They just figured on yours, if they replace both board they will have it fixed, but will they as it maybe a simple fix like a broken wire so it is not getting any power which they will repair when the 2 boards didn't fix the problem.
I used to repair TV until the new digitalis one came out as this is micro circuity and cost more to get the tools to work on them then you could ever collect enough to come out on the deal from what new ones cost. When I was repairing the reg TV I got in many that were told they cost more then what they are worth, but were simple fixes like bad connection circuit boards I just had to re solder and worked like new. The reason they were told it was not worth fixing as the shops didn't want to spend the time finding the problem. Several the back were not even taken off or you think they would see the fuse was blown as most from use the fuse get weak and they are fuse so very close to the start up AMP they will blow when the fuse get slightly weak.
Anyway the problem is most things are throwaway as the labor cost is much too much so they make the product so when it goes bad to throw it away and not repair it. Some things there are parts for them for maybe a year or 2 then parts are not available.This is real true to detectors and IC chips as they will order like 4000 and when they run out, they are out and have to order 4000 again in order for them to be made which is not feasible as by then there is a new model out that don't use that chip, but a different one.
Time for me to get off my soap box, but I just had to say my 2 cent worth.
Rick