1987 jeep Cherokee 6cyl motor help ?

my buddies jeep spun his harmonic balancer the other day and when we put the pulley puller on it the serpentine belt part broke off and the shaft part is still connected to the crank? tried using sum pb blaster and a pry bar nothing, tapping with a hammer nothing, was wondering if there were any experienced mechanics that might have a solution other than pulling the motor or trying to take the crank off still sitting in the jeep, i was thinking maybe try to sneak a grinder in there and make a lip for the pully puller to make another attempt at, lemmi know what u think thanks