Best thing to do before you use the washing machine is to clean out the soap trays and run a 95deg wash. don’t use any detergent run it empty, you can put white vinegar in to help shift old caked detergent or use one of the proprietry cleaners then run a rinse cycle.
The worst thing you can do is have any old soap left in the machine.
If you look for Goretex.com they have a page for cleaning instructions the same applies to the protak.
Tumble dry afterwards this helps to ‘wake up’ the fabric and set the repellant layer again. Don’t drip dry or peg out.