The "wiper governor" name is a bit misleading. It's basically the intermittant wiper
control module. The problem you describe could be caused by either the governor or the
park switch in the wiper motor itself. Loose contacts in the switch can cause this,
but you've ruled that out.
 Without being able to do any testing on the system, my money would be on the wiper
motor. Governor failures "usually" show up as wipers not functioning at all or not
turning off at all, and arent really common (in my personal experience). The park
switch contacts in the motor can break off and short inside the switch causing
intermittant pulsing. If you live in a snowy climate, snow packed under the wiper
blades can cause damage to the contacts.
 I would suggest finding a wiring diagram and properly testing the system. If you are
unable to do this, a used governor shouldn't be more than about $10 at the local junk
yard. If that doesn't solve the problem, a new or rebuilt wiper motor is in order.