This HDX900 was very well maintained by Paul Celona at Macie Video Services.  I was always able to have the cost of the service paid for by the production is was on so it was serviced between every season. 

I just tested it using a blank DVC Pro Tape and it records and plays back fine.  No issues with the SDI port.  I cannot find anywhere online that shows how to check the hours, but we've had the heads and recording head replaced whenever it showed signs of wear.

The viewfinder is a Panasonic AJ-HVP20P which also works with no issue. 

Please let me know if you have any questions.