Washed it with Nikwax tech wash, then treated it by washing it with Nikwax wash in waterproofer. Just remove the armour and bung it in.................... After reading the label of course.
It is recommended that you do clean gortex to keep the pores unclogged............. I have washed my Gortex Pro Shell jacket a few times............... Still good.
*edit*....... Just to add......... You must wash Gortex with an approved cleaner. NOT DETERGENT, as it will block the pores. I use Nikwax Tech Wash.
I've always washed my Goretex garments in the washing machine, 2 x quick wash cycles at 30 degrees; first wash in plain soap flakes, second cycle in Nikwax wash in waterproofer.
Done all my snowboarding, walking & motorcycling gear in exactly the same way for more years than I can remember.