I know this sounds stupid, and I'm sorry if it does. But I didn't see it in the body of your message.
Is the oil level in the transmission back to normal? When you pull out the plug on the side, the level should be to the bottom of the hole.
Okay, next question, what did you use to refill it with? I was advised to use 90 weight gear oil.
Finally, I find that using a tube of BG gear lube is some of the best medicine for an old transmission. Try it, the stuff is fantastic.
