GE 7 HP Speed Sensor Magnet replacement

Hi all, just finished taking apart my GEM E6 7HP GE motor to clean the brush holders. I put everything back toguether and went for a drive but now I am getting an error 81. I am pretty sure I damaged the magnet on the motor. Where can I get a replacement and how Do I replace it? Glued on? by pressure?

Thanks in advance!

Take the tach sensor off the cover of the motor. The magnet is held on with a 1/4 20 cap screw. I have magnets $25 plus $8 postage