This may sound hard or a little out there but ive seen it work. I would Soak it with Kano oil or PB Blaster in the set screw hole the shaft. Then take a pair of channel lock an rubber mallet or brass hammer and tap TAP on the shaft It may take an extra pair of hands but Holding PTO and leting the weight of the motor do most of the work and tap on the saft it may come out i would try this before i go drilling holes
