Read your first post again. Are you sure it's not something as simple as the deflection on your belt? You said that seemed fine, but IDK?
Is she right! Yes, that is just one of your problems.
I read your post again too.
I think the Sea Foam is your biggest mistake,
If it has broken down all the sludge in your gas tank, it has clogged up your fuel lines
And probably your filter too,
And it for sure is clogging up the jets in your carburetor.
Sounds like you need to pull that gas tank and clean it right,
Don’t clean the fuel line,THROUGH IT AWAY with the fuel filter,
Then pull the carburetor and clean it.
Then buy the right belt.
If the tank is rusted inside you may never get it cleaned good enough.
BUY A NEW ONE.