I agree with the post above - I have joined and I have looked all over the discussion page for how I might respond to the discussion - there is no "Post Comment" window available to me. So I logged out and logged back in to see if the choices would change - no change. I will try back tomorrow and see if the discussions that I'm interested in posting to have a "Post a Comment" section avaialbe then.
Update - looking more at the discussion that I wanted to post to it appears that there is a "Conversation Closed" type of condition that can happen after 400+ posts.
So I will attempt to use the "Continue Conversation" and start a new thread to continue posts on this ailment. Thx
Update #2 - my attempt to continue the discussion that I was interested in was successful. I copied the same thread name over and added "(Part 2)". Thx