We took off the pan and changed the filter. Still no go. I did notice that the new filter seemed to have filter type material inside whereas the old one did not. Could that filter material have broken down and caused a clog somewhere? I will look into the linkage. Would it make sense that it would pop while driving? We were in drive going up a hill when it "disengaged". I am trying to believe that the trans has not just checked out as it was exhibiting no problems up until it just stopped engaging entirely.