Hi Sharon,
From your question, I'm assuming the model number is in fact APL 8124/1?
I've not got any precise instructions as I've not worked on one of your machines before, but a job like this would normally involve locating the screws around the back edges of the door, which will then need removing with a T20 torx bit screwdriver, and this will seperate the front panel of the door and allow you access to the door handle fixings. It will be obvious once you have opened up the front door panel on how to swap handle.
Rupert, June 2020
