If you are talking about the bulb type seal that is on the outer edge of the wipe seal they are not hard to replace. I had to fix one of ours on our kitchen slide just this spring. Ours was attached with a screw at both ends and then the screw at the top and where the seal meet the seal that went across the top of the slide, were covered with some type of hard black silicone. I took a razor knife and cut the silicone between the two seals and removed the two screws and slide the seal out of the channel. To replace I used a little silicone spray lube just so it would slide easier up the channel, put the screws back in and then used some clear silicone over the screw and at the edge where the two seals meet. Pretty simple and took me about 5-10 minutes to do. The picture isn't from my trailer but is the same as what I have on my trailer. I hope that helps.
Phil & Janine
2004 Chevy Silverado 2500HD Duramax
2014 Cruiser 333RL