Been trying to figure out for the longest time where that pesky clunking sound was coming from up front. Of all things it was the right motor mount! The rubber was gone and it was just resting on the frame. Easy to replace. A pic of old and new:

 

There is a lot of clunking in these machines! Glad you found yours!!

 

Glad I read your thread, I'm about to start searching for my annoying clunk today. Doesn't happen all the time but when it does its annoying. That will be the first place I will look, Thanks