Thanks daviedog. After close inspection, I've decided I want three new gus switches now...
My heavy handedness has given some dents to the threading. Not on the outside where the tubes make contact.
They are on the insides so you can't see it but i know it's there
Now you do too.
Good to know for the future though
For someone so particular about any blemish, you sure are hard on your stuff! Can't say I have ever damaged any threading on a mech.
Hope you get it sorted soon though matey.