Hello CANES RR,
On your problem with the MTH loco, one of your wheel sets may be gauged just a tad too wide. That, combined with the switch guardrails allowing too much room, is probably what's causing your loco to hang up. Putting some spacers on the guardrails would help cure this problem. This is one of the issues addressed here: https://ogrforum.ogaugerr.com/...h-problems-revisited
As far as your switch not fully throwing, are you running enough voltage to it? I had the same problem early on with some of my switches. At first I was running conventional and tried to power them with track voltage. That didn't work so well. Then I tried hooking them up to 10 volt constant power (indeed, the instructions say they will work on 10 volts). This vastly improved operation, but I still had a switch or two that didn't always fully throw, just like yours. I finally started running them at a full 14 volts, and haven't had a problem since - they snap with authority.
See if this stuff doesn't help before starting to bend and file components.