E-studio 810 problem
There are a couple of different switches that could be out of alignment, or not "making" when you reconnect the finisher. If you will look on the copier, at the latch that connects the finisher to the machine, you will see a pointy shaft about 2 inches long. This rod comes in contact with a switch inside the finisher. There is a metal actuator on this switch that could need adjusting. Not a difficult job, but it will require you to take a few covers off. Also, there is a black push button on the finisher that is actuated when you push the finisher to the machine. If you are looking at the back of the finisher (the side that connects to the machine) it will be on the lower right hand side. It it operated by a connecting rod inside the finisher. This rod could have come loose. Again, not hard, but requires cover removal. Also, when you locate this particular push button, try manualy pushing the switch to see if this makes you message go away.
As for the black spots, this could be any number of things, but I suspect that that it might need a cleaning blade and brush, and maybe just a good cleaning in and around the drum unit.
Hope this helps,