Drysuit seals are not too difficult to replace yourself. (The tough part is doing it cleanly, without globs of AquaSeal oozing out all over.) The job does require a few items to help position and hold the new seal in place while the sealant dries. The wrist and ankle seals can be held in place by using approximately six-inch long, round foam plugs, cut to a slight taper. I turn the sleeves/legs inside-out, insert the plugs to hold the fabric, apply the sealant, put the latex seal in place, and let dry. For the neck, I use a plexiglass plate, cut a couple inches wider than the diameter of the neck opening in the goretex. Again, I turn the suit inside-out, then place the plate inside the neck and, using double-sided tape, secure the neck opening to the plate, maintaining its round shape. Apply the sealant, then put the latex seal in place. I use a 2 inch high foam ring, cut to the same outside diameter as the plexiglass plate, to secure the seal while drying. The ring has about an 8 inch opening in the middle. I place the ring on top of the seal (Create a sandwich between plexiglass base plate, sealant, latex seal, and foam ring. The opening in the middle of the ring gives the neck tube of the seal a place to go.) I put some weight on top of the foam to hold it all in place while it dries.
Of course, another key to success is prep. Many people cut the old seals at the edge of the goretex fabric, but I have been able to successfully remove the entire seal by working at it extremely carefully, taking care not to tear the drysuit fabric. Make sure that the surfaces are clean (including the new seals) and then wipe with solvent before applying the AquaSeal.
As with anything, it's tough to explain with words. Let me know what points might need a little clarification.
As for care and feeding of the suit, sunlight is the killer of latex. Store the suit in a dry, dark place when not in use. Be sure that it is not a damp place and be sure that the suit is dried before putting away. (Mildew will kill waterproof fabric.) You can also apply a protectant like 303 to the seals to help prevent them from drying out.
