My game had a similar problem. Verify that the castle door and VUK cable is connected to the correct position of the board under the playfield. The board has a row of 7 connectors. One of them is not used, it has a red stripe. The VUK cable connects beside the unused connector, it has a brown stripe. In my game the VUK was connected to the red connector and the castle doors and VUK operated continuously after power on. Moving it from red to brown corrected the problem.