Product review (3 stars): Get a Glue Stick before you start or you'll be sorry -- those little pieces have wings!
Before you even start, get a glue stick -- just a regular glue stick, the kind kids use for paper. Because as so many other reviewers have said, those little pottery pieces fly all over the place. There is nothing to hold them in until the coupler is completely reassembled. At t least one will fly out every single time you push down the spring. You have to hold it perfectly level -- not one degree off. Working over a basin doesn't help. The spring propels them like a slingshot. I chased them around for 40 minutes before i thought  'glue stick!!'. But don't use strong glue. The buggers are porous and you need to get them out when they break again. The kit works, I'm glad I bought it, but I'm so ticked off.
1) Ninety per cent of those who buy it need only one or two of the little pottery bits and if they cost more than a penny to make all four I'd be shocked --  in a US factory, with US labor. The other 10% need the washer/gasket thing so what's fair? Fifty cents sound okay? $16.50 is outrageous. If I could buy a collar kit with the ball bearings they formerly used for these collars I'd gladly pay $35 but the bits break repeatedly.
2) If I'm going to be ripped off, I want instructions and at least one extra pottery bit -- even at Ikea they give you a couple of extra screws and these bits are 1/10 the size of a screw.
3) While I realize the kit manufacturer is to blame for not including instructions, the seller doesn't have to ship them that way. Three sets of instructions would fit on a single sheet of paper. At least warn people how easily those bits get lost.
There is a slip included in the package that says how to remove the existing coupler and advises reversing the steps.  It doesn't mention the rubber gasket. You can't see that it's folded until after you've removed it and failed to note whether the fold goes up or down. It's not in the drawing. The plastic collar is in the drawing -- upside down. Anyhow, don't put the bits back in reverse order. It's easier to wait till you're ready to put the plastic collar back on.
4)Keep the old.  Only one of my bits was broken so unless three of the new ones break at once, I can use them again.
This is my second GE dw with a broken coupler. The first was a year old and I threw it out because GE told me this kit wouldn't work and I had to buy a new hose for $90. I might have, but  the build quality of this DW is so bad, there isn't a metal panel you can remove to access the hose hookup. You have to remove the entire outside housing which is a million steps and because it's a piece of junk it had dents. I had no faith I could get it back on again.
So I bought the same dw with fewer dents on Craigslist for $125. Six months later, the coupler broke. An open jar of mayonnaise lasts  longer.
Meanwhile, the GE DW I bought in 1985 is still running perfectly. I gave it to my brother when I moved to a house with a built-in.  It sounds like there's a tidal wave in there (it sounded the same when it was new), but you've never seen such clean dishes in your life.