Your M25 should be like my M30....
The centerboard pennant is a stainless wire that is epoxyed through a stainless tube that runs in a packing gland. If the pennant is broken, the best way to repair is to detach the pennant from the winch, remove the stainless tube, and replace the entire stainless wire.To accomplish this the boat must be hauled. Since this is a job that needs to be done every 3-5 years, I would cut the cable inside the bilge area and form a loop with a thimble for easy connection to a second piece of wire that will be put through the tube. this way you don't have to mess with the winch connection of the wire at each replacement.The old wire can be removed from the tube by heating the tube with a torch and while holding the wire in a vise pull on the tube. Clean out the inside of the tube with a piece of threaded rod in an electric drill.Cut and form the loop for the centerboard connection and place the new cable in the tube with the proper length exposed. Fill the tube with epoxy. Be sure to have the cable and the tube in-line with each other so that the wire is not exiting the tube at an angle. This would cause a bending stress on the cable and lead to premature failure. The best way I found is to hand the cable with a weight on the end, put a tempory clamp on the cable at the correct point under the tube, seal the end of the tube with plumbers putty, and then pour the mied epoxy in the top of the tube until full.The centerboard does not have to be dropped to attach the pennant, but you probably drop the board every time you bottom paint anyway.Coat the underwater exposed wire with pitch tar to retard corrosion.In the bilge, form a loop with a thimble and connect to the existing end of the cable from the centerboard cockpit winch, making sure that the centerboard will completely retract.I used to recoat the underwater wire with pitch tar every year at painting, and replace the wire whether it needed it or not every 4-5 years.The correct length of the wire on each side of the stainless tube should be available on the Morgan owners website.