@NolaMel I'd be
very surprised if you broke anything. While that pin wasn't supposed to be tampered with it
has a user friendly unscrewing method so they'd have to have had that in mind. Breaking the insulator isn't particularly easy, the material is fairly tough for as little as there is in there.
Make sure you caught the threads right and didn't cross, while the pin is out try to see what's in there and if everything is seated well.
In conclusion: on a "production" device never change anything without a good reason (eg it's hoopajooped anyways). Don't assume you need to turn a screw just because you can

(long time carburettor experience speaking

).
If it's just a device for experiments - have at it then.