On the neck seal, if you separated the two rings that sandwich the seal you're more than half way there. It helps to heat up the glue with a heat gun and then work them apart with a screwdriver or other blunt edged pry tool. Depending on the type of glue DUI used, sometimes they go easily and sometimes you have to keep heating and working your way around to get them apart.
To grind the old seal off it's helpful to have a small bench top belt sander or at least a Dremel with a sanding tip. Develop a smooth, even surface to glue the new seal to.
Take the new seal and prep by roughing up the surfaces to be glued with 80 grit, cleaning with solvent (Toluene if possible or MEK or acetone etc). Clean the surface of the zip rings with solvent as well.
To mount the new seal, it's very helpful to have a flexible plastic ring the same diameter as the zip ring that will support the new seal when you glue to zip ring to it. DUI sells these rings but you can make them out of any thin plastic (like an old storage bin). Mark the plastic using one of the zip rings as a template and cut it out.
Stick some double sided carpet on one side of the plastic ring and use the tape to mount the new seal to the ring evenly.
Apply 3 coats of contact cement (aka neoprene cement) around the edge of the seal and around one of the rings. Allow the glue to dry between coats, except the last coat which should be tacky (about 5 mins).
Stick the zip ring onto the seal. Using a hand roller or your thumb, work your way around the ring and ensure a good connection between the glued surfaces. Remove the plastic support ring from the seal.
Most seals are larger in diameter than the zip ring so trim off any excess.
Repeat the gluing procedure for the other side of the seal and the second half of the zip ring. You don't need the plastic ring for the second side as the first zip ring is supporting the seal.
Wrist Seals
Recycling the wrist zip seals follows much the same procedure as attaching wrist seals to a suit.
The key to an easy installation is to find some supports (aka mandrels) that are almost exactly the same diameter as the rings. Plastic cups, soda bottles, PVC pipe are potential mandrels. Ideally they have a slight taper and fit snugly inside the rings. The mandrel should extend at least a couple of inches beyond the end of the ring.
Prep the surfaces to be glued as above (sand and solvent).
With the mandrel snugly inside the zip ring, mount the new seal on the mandrel with a 1" overlap. If the wrist seal is significantly wider than the zip seal you will have to trim off the excess to the point where the diameter matches the zip seal.
When they are matched up, keep the zip ring and wrist seal in place with strong rubber bands.
Roll the wrist seal down to expose the edge of the zip ring underneath. The edge of the zip ring and the rolled down edge of the seal should be butted up together.
Apply 3 layers of contact cement to the zip ring and wrist seal, allowing the first two to dry and the third to go tacky.
Carefully roll the edge of the wrist seal up so it sticks to the zip ring. Be careful to roll the seal up evenly.
Using a roller or your thumb, work around the joint to ensure a good connection.
Allow the glue to cure overnight before removing the mandrel from the wrist seal.
Let me know if you have questions or if I didn't explain something clearly.
