I use a large syringe, at the end I use a rubber band to hold on one of the condoms from a carto, this creates a seal to the carto (read you can use pencil grip too)...I use water heated in microwave to flush out the cartos, push out excess water by plunging air through several times...then I dry in a toaster oven, 250 for about an hour. When draw is too tight, I pitch..
I DIY..will use attys to test, but sometimes you have to test on cartos..hate getting a new one out, so I use washed ones for testing juices. I have some that have been washed 5-6 maybe more times no problem..though it's possible they weren't actually used very long between washes. I just know I keep seeing the same logo'd one that I swear has been reused for months!