About a year and a half ago I bought a Kato GG1 a beautiful engine with, as I felt, one drawback the couplers. It didn't get them to work alright every time with those cars that had Micro Trains couplers. I tried to look around on the internet but I couldn't find any info on what to change to. Then the other day I decided to give it my best shot. I figured that I could possibly fit an MTL 1128 in the pilot truck. This however turned out not to be the case.
The original coupler
To change couplers you just need two small screwdrivers, a file, a knife and a pair of MTL 1023 couplers. First insert the screwdriver between truck and body
Removing pilot truck
Then you gently turn the screwdriver and the truck pops off. No force is required to do this. Then you can remove the plough from the engine. It snaps into the sides of the footsteps on the pilot truck and into two pin at the top of the ctruck chassie, again no force is needed. Then it is time to remove the original couplers using the screwdriver. When you have done this you’ll see that draft gear box has two clamps on the top a pin in the middle and one in the rear part of the draft gear box.
Clamps and pin in draft gear box
At this point I removed the pin in the rear part of the draft gear box. Then I placed the MTL coupler in the box lightly pushing the clamps in the gear box aside. If you push the MTL coupler too hard the lid of this may come loose (it did for me, but it was easily repaired with my soldering iron). Then it is time to reassemble the truck on the engine. Leave the plough on the table for now. The opening in the plough is too narrow for the MTL coupler so you'll have to widen it with the file. If this opening is too small in height it can result in the truck not being level on the track. So you will have to test this size, I guess that about 5mm is how big I made this.
The plough as it was on top after modification below
Then replace the plough and check that the truck is level when placed on the track. If not you may have to adjust the opening for the coupler. If it is to low it will force the coupler up and tilting the truck with it.
Hope this can help someone.