Going back to my varnish post, the varnish in the oil is soft particulate that is much smaller than any clearance in the transmission. If transmission fluid got in there, the varnish is in there too. And if it's colder, it will have deposited a thicker layer.
In my experience the carb cleaner in a bucket is inferior to any cheap WalMart carb cleaner in a spray can, for cleaning varnish off the inside of a block or transmission. You'll see what works.
