We have guys on here that can tell you the most obscure information on a rare mini variant, it's problems, and how to fix time...but there are not as many people active on this forum that specialize in diagnosing BMW mini issues.  You might get an answer eventually, but I would try asking on a forum that has more of a focus on that end of business.  I have not really used them much, but Northamericanmotoring.com might be a good place to start.

What could cause a forecful down shift in a mini s?