THERE ARE NO " CORONA WIRES " IN THE DC 250 SO YOU CAN STOP LOOKING FOR THEM !
static is rare on these units,
confirm that you are setting the paper tray to the correct stock that is loaded in the tray- 85% of the time customers are loading a heavyweight paper in the trays or bypass tray and leaving the machine set at plain bond paper ! if the stock is too heavy to duplex people try to tell it a lighter weight stock to try and get it threw the machine this will not work !
the best way is to use the bypass tray for both sides on heaviest of your stocks
if it is not duplexing regular paper i suspect some slippage buring the inversion of the paper so the cleaning of any rollers in side the right hand door or ultimateley replacement of the rollers !
hope this helps ! these are a dream unit to work on and copy quality is superb ! one of the best machines i have seen in my 30 years !