Yes, I've done that to some of my 1 Gauge locos quite a few times. Since G1 locos are relatively heavy (and expensive!), handling and unmounting and mounting them on their bases can cause small pieces to break off and or break entirely. Sometimes they can be glued back on, sometimes I don't bother as I know they will come off again.

You certainly quickly learn where you can handle them and where you can't due to breakages (although the manuals give some guidance on correct handling). After a show where we have G1 locos running we always perform a layout and floor inspection looking for pieces that have come off locos and coaches / freight cars, as we know it inevitably happens.

I've only had one instance of where stuff got broken off due to someone else mis-opperating a loco. I think they were trying to find a loco's address by calling addresses up on the controller and setting a speed. In doing this they accidentally called up my loco and drove it into the turntable pit off the turntable spur where it had been parked. Although this broke stuff off the loco, at least it wasn't driven in the opposite direction because if that had happened the loco would have driven off the layout on to the floor (we had no stop buffers on the track, which we make sure we do now...). However I recall someone else catching another rather expensive loco in time before it hit the floor due to the same person dailing up locos on the controller somewhat willy nilly - in fairness to them they were around the far end of the layout and might not have been able to see the turntable area and been aware of the havoc they were causing.

We now make sure we publish lists of loco addresses, and restrict who has access to controllers. Letting kids play with wireless remotes unsupervised can also cause trains to rear end another train, so we avoid doing that!

I have also broken my 1 Gauge 54325 DB BR 260 switch engines plastic handrail by mistake. Why Märklin doesn't make these also from metal like the loco body is made of? It was almost factory new when this happened...

The best way to handle gauge one is not to handle them! That being said, many guys on the live steam side of gauge one make a carrier that can be placed on the track and the model ran up a ramp and into the carrier without touching or at the most, pushing it from the end carefully. I have seen one that would make contact with the rails to provide power to the ramp and carrier rails so that a powered model could be driven up into the carrier. Once in the carrier, the end ramp was folded up and latched and the model carried in the carrier without ever touching it. Not sure one could do this in HO scale, but anything is possible. Mike