Your tolerance here please, yes I have Model T's and read this site each day.
I was plowing snow with a Farmall Cub tractor and though there was a slight noise that would go away with slight pressure on the clutch pedal. I pulled it into the pole barn and went into neutral and let the clutch out and there was a terrific rattle.
A few years ago I split the tractor for a rear main seal leak and while in there put in a new clutch and pressure plate and it doesn't have many hours on it. Today I removed the hand hole access and the throw out bearing (graphite) seems all there. Does this sound like a clutch finger adjustment with noise when the clutch pedal is released or something else? I can do the finger adjustment without splitting the tractor with a second person but it is not easy. Otherwise I need to move it to another building and the blade is on the ground so that is a problem.
Shifts fine with no grinding and I can let it sit until spring as I have a bigger tractor to plow with but like a second machine available if one won't start. I would like to know what these symptoms might be before I go to lots of work to move it and take space in the garage where I have heat.
Did you replace the pilot bearing when you serviced the clutch?
Flywheel bolts.loose & or broken.
Could be pressure plate bolts too.
Sounds like a finger "mouse trap" spring broke, or a finger itself has come off of the pressure plate where it pivots. You should be able to see either of those scenarios through the clean-out though..
Jack the blade up and secure it in the raised position with a ratchet strap to move it.
Glad to hear your T/O bearing is ok, those graphite throw-out bearings for cubs are getting expensive!
Get out your splitting stands and split the tractor. I have had more than one Cub throw-out bearing seem "all there" and in fact not be there at all. Some of the "newer" pressure plates for the Cub have had a finger "issue" with them breaking. Before splitting the tractor, hop over to farmallcub.com they have a great forum and lots of technical support for the Cub on the website.
Definitely though, there is no such thing as a "terrific" rattle, horrific maybe. Split the tractor and find out what broke.
Just be sure if you replace the throw out to soak it in oil for a day or two.
Let Rachel fix it!