Not knowing much about Peco switch (or point) motors (or machines as they are called here in the US), I’m wondering if you used a common power feed to supply electricity to the motors? If you did, can you determine if you switched the wiring accidentally so that some machines receive the ‘negative’ power on some terminals and ‘positive’ power on the same terminals on different machines? This could essentially could cause a short circuit because of the wiring/power mismatch between the machines even if you aren’t activating it.

You might want to disconnect ALL the switch machines (ya, I know, that stinks) and reconnect one at a time and test it’s operation as you move down the line reconnecting each one. Get each one working correctly before moving on to the next and then check them all together as each ‘new’ one is added. That way you’ll know which is the trouble maker before you move on.

Hope this helps,

Geof in the US