Any gs-4 with apart number different from 0301 last 4 digits is a fixed dcc problem
That is correct....to a degree.
The first half of 126-0301's were delivered without dcc spacers. (and there were a LOT apon initial release before the issue was noticed). Kato offered the O7-2008 spacer kit for those who needed them (they were pretty much depleted when I left Kato a year and a half ago but they're out there).
Now, the second half of 126-0301's had dcc spacers installed at the factory before they were shipped as the issue was apparent by this point. They are slightly different shaped. I can tell them apart pretty easily. That said, for all intents and purposes, they're the same. A LOT of Kato/Digitrax EM13 motor function decoders got smoked because of the original design.
Lets move to the wartime black GS4's that came out a couple years later...although the upper frame halves were modified for the dcc friendliness issues...someone at the factory grabbed a couple bins of old frame halves and there are some floating around with 1 early frame half, some with the other and a few with both. After we realized this problem, I went through the rest of the wartime black units Kato had onhand at the time and installed spacers in the units that needed them. That said, there are more out there. We were told by the factory that there were no more than 50 units like this, to which I observerved as incorrect as I personally retrofitted over 100 units.
On the updated drivers/split axle issues....I want to say up through about 126-0308 (and 126-0311 freedom train unit) the original plastic sleeve axles are prone to crack. Not as in 'if you handle this rough, they will crack' but more of a question of *when* they will crack. I've pulled new old stock units out of the box with split axles so it's not a usage thing, although that doesn't help either.
The driver were redesigned around the time the FEF3 was being designed and Kato USA got a TON of revised drivers sent to them from the factory. As warranty replacements. Which they promptly sold to people. Generally i'd write off the cost of GS4s coming in for driver replacement well out of the warranty period but got overruled more than a couple of times for that. That said, if you have an early GS4, expect to replace the drivers with the revised ones. They're $15 a set. (Kato part number 932035). Later units came with these on there. You may have to add a spacer to the 4th driver as the bearings used in the revised drivers like to slope inwards. I use a piece of cut down tube as a sleeve to hold everything where it should be.
Ah memories (and much gray hair) over the GS4!
If someone runs into a brick wall and doesn't want to re-driver their GS4 or wants to install ESU LokSound, I can certainly help you out. I've repaired and installed sound in hundreds of GS4s and do it all of the time...just not for Kato anymore.
Enjoy!
Kelley.
