Something to try in the sim which was used on the 737-300 in the 1980’s. In the event of a full nose down stabiliser jam. Try getting the pnf to put his lap strap around the control column. ( pnf will have to move seat fwd & possibly extend the belt) Pnf then moves their seat back to take the “weight” from the column. PF should find the aircraft will fly virtually hands free. PF will find he has some fwd & aft movement of the control column to enable normal flight, but a little bit more adjustment can be made by the pnf by moving the belt either up or down the control column. Once all QRH drills etc have been done at about 500ft on finals PF prepares to take the weight & gets PNF to release the belt & strap themselves in for landing.
(It works & takes the effort out of the excercise some trainers dislike it for various reasons. Imho make use of anything that can help the situation)