The Marx 1590 is the best O27 switch ever made. It’s durable, works well with all makes of trains (just put a track pin in the center rail where the switch pivots so that Lionel trains can pass), and can run off accessory power without modification.
The only downside is that it (allegedly) can’t be set to automatically switch to a position to accommodate an approaching train like a Lionel 1122, which makes it unusable in a reverse loop. That’s true if you wire them the way Marx said to wire them.
Here’s how I wire them to get that coveted feature.
