The heater resistor pack shoulden't be a hastle to remove.

You just need to drop the glove box, same applies to the fuses.

The motor is up in the dash, the "Scretching" is most likely water ingress into the motor via the pollen filter which has caused the motor to become tight, these just arn't fitted properly with a new seal in alot of cases, so you need to address this along with lubricating the motor, as just replacing the resistor pack isn't actually fixing the problem.

There is a thread on here where another Martin has posted pictures of how to remove the motor, just do a search.

Martin