E60 transmission cable adjustment

[Bidz]

HI ALL, I HAVE RECENTLY HAD A FAULTY SHIFTER UNIT AND SO REPLACED IT WITH A 2ND HAND UNIT, SINCE THEN IM HAVING SELECTION ISSUES,....FOR THR FIRST 5 MILES OR SO ITS DRIVING AND CHANGING GEAR FINE BUT THEN WILL GO INTO A MYTERY NAUTRAL WITH NO DRIVE!,
i HAVE TO ROLL TO A STOP AND AFTER SELECTING PARK AND BACK TO DRIVE I GET THE "TRANSMISSION FAULT RED COG" POP UP AND IT STILL DRIVES BUT OBVIOUSLY NOT GREAT.........
SO IM GUESSING THE CABLE REQUIRES ADJUSTMENT,............HAS ANYONE GOT THE CORRECT ADJUSTMENT METHOD FOR THIS PROCEDURE
MANY THANKS IN ADVANCE 👍😁