Another problem can be that sliding shoe activated couplers going over certain switches can cause the coupler to activate. This, in my case, is mostly true with my Atlas switch tracks. I hate the sound of an engine smacking into the rear of a string of detached cars. My stomach turned when I heard this happen to the rear end of my green 2400 observation car. The sinking feeling came knowing that there was no rear coupler protecting the car from the engine's impact. There was only a minimal paint chip as a result, but I imagined much worse until I looked at the car. Even this small damage was upsetting. This vintage of cars I run are in high end collector condition so that pits my stomach. I'm past worrying about the damage to the resale price; it's more the damage to what I consider vintage industrial art.
The solution that I came up with is to string small cable ties around the coupler plate and through the groove in the sliding shoe. This elevates the shoe as well as acting as an insulator over the contact. Elevating the shoe is important because sometimes having the shoe catch on modern track can rip it off. Also the cable ties smooths out the groove in the shoe so that there a lot less edge in the shoe to catch on the track.
Alan
