Grace Wines

Hi Guys, hoping someone might be able to answer my problem as I can't find anyone who knows what's up! I'm having a problem with my DeWalt Circular Saw DWE576, I purchased recently with two rail guides. The edge of the splinter guard never seems to align up to the blade of the saw. So when it comes to placing the rail guide onto the mark, it never cuts on the line, always a few mm off? I followed the instructions, set the blade depth, adjusted the cams and slowly cut the rubber strip fully on a sacrificial piece of wood, but time after time when I use my rail I notice the rubber strip seems to get thinner and thinner. Now when I set my rubber strip to the mark and expect a clean cut to the line (as you should right?) It's actually 2mm out, which just defeats the quick and easy point of having a rail guide. I always start cutting into the wood when both cams are on the rail so there's no chance of side to side movement, and I let the blade finish before I take it off the rail in case of any kickback or unwanted accidental cuts. I bought a new rubber strip to replace the old one hoping it wouldn't happen again but it did! Don't want to buy a 3rd and it happen again 😅 can anyone give me any advice please? Thanks!