It's a Mark II. Actually the problem has been identified, I think... This is related to my Ignition Sense problem in another post. Apparently, my AC adaptor terminal always thinks it's connected to AC power. Hugo and Rob have been very helpful so far in helping me diagnose this problem, but it looks as if I may be sending it off to be fixed. At least their turnaround is very reasonable. I will post here with status, in case anyone else runs into this problem.

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MkII 080000554