Have you cleaned or lubed the pratt muffler arm, It will do just as you described when corrosion gets in between the rivets on the arm take a little spray lube and spry the pivots on both sides and work it up and down with your hands that should do it.

The bottom of the felt strip is stationary so it can't move away from the head therefore the very bottom of the strip would always have some contact with the head. If the felt strip has stretched it would also effect how much of it is pulled away from the head as you decrease the contact angle by loosening the knob.

When you say the arm, do you mean the muffler knob itself? Like I said, it detaches when its upside down; so the mechanism seems to work, but when upright the felt strip doesn't detach from the top. How does lubrication fix this?

Thank You!

No I am talking about what the felt strip is attached to, the two rivets that holds the arm on both side just a tad of lube sprayed into those points will help it move more freely/ My 50's pratt muffler was doing exactly as described, I cleaned it with a towel then a shot of spray lube on both pivots, worked it up and down by hand, it has worked perfectly ever since.

Thank You!! I'll work on it today and let you know how it turns out!

Okay, so I lubed all the parts on the muffler, but I did notice that when I tighten the muffler, it pushes against the head, but when I loosen the muffler, it seems to collapse in the middle and fall away from the head. I loosened and tightened the muffler without the head on the batter side, and it works, but is it supposed to almost bend in the middle when you loosen the muffler? I'm pretty certain I have it on correctly.

Thanks.

Here look at this.

That's how mine looks. I tried it again with the head on it, and it worked. It tightens against the head, and it just fell away from the head when I loosened it.

Thanks a million!

That is what we are here for, glad to be of help !