I had this exact same issue with the HVF.. Tech came out 4 times, each time it would work for a while but eventually it would come back with same error.
The end result was the tech replacing the entire finisher under warranty.
I have a ColorQube 9303 machine attached to a high-volume finisher. The display is showing the following error message: "Finisher Main Tray out of service. Check for obstructions in the Main Tray." Copies and prints are coming out of the top finisher tray only and the stapling function has become disabled. A Xerox technician came and worked on this last week and it was corrected for a day or so but the issue has returned. I checked for obstructing staples and paper...and also reset all software. I didn't find any obstructions and the reset did not do any good. I will be calling the technician back but just seeing if anyone has any advice on here.
Thanks,