Overheated water shutter debris removal

[CDNSPORTSTER]

Hello all, I'm not only new to the forum but also a new -1st time boat owner.
Issue;
Overheated the Yamaha L4 3.0, (water pump drive belt failed)
Belt replaced along with a 140* Thermostat.
Prior to the Overheat, it always ran at 140*, now runs at 150*+, not the same power, and a very different exhaust note. not a pleasant one - more aggressive for lack of a better way of describing it.
I removed the rubber exhaust coupler to replace what I expected to be a burnt - damaged- stuck, water shutter.
The Metal shutter is all there, it pivots fine, however - no rubber to be seen at all.
Not the Grommets or the rubber that should be all around the edge of the shutter plate - nothin'.
What am I looking at as far as finding the rubber debris? I am assuming this is causing the exhaust note, temp change etc...
Will the leg have to be removed? - I am really hoping to avoid this as I'm worried about finding seals / gaskets for this Yamaha outdrive.
Any chance the debris has made it's way to the exhaust ports just behind the prop? I haven't checked as the boat is in the water.
Thoughts..?
Thank you in advance.

 

[Scott Danforth]

Running without water you burned all the rubber bits between the elbow and the drive

This is the rubber hoses, the rubber bellows and the rubber on the flapper.

So get to replacing the rubber bits

 

[CDNSPORTSTER]

Thanks Scott,
I have a new shutter, couplers etc. As you said "Burnt up all the rubber bits..."
Do I need to be concerned about where the rubber debris has ended up?