I believe you may also need a license to buy Freeze 12.
I have got a license, but the Napa store I buy it from they never ask me to see my license, so I'm not sure.
Definately change the accumalotor and you will also need an orfice tube.
The replacement accumator wont look like the original and will come with an extra tube to make it hook up.
I actually took an old original accumator, cut it open and replaced the dececant bag. Then welded it back together.
There's actually a little more detail's than that, but that's basically how I done it.
A couple of pictures.