I have a different boat, but the problem seems universal. The original roller wheel is likely inset into the door and was intended to roll on a brass rail in the door threshold. The wheels stop rotating and soon get flat spots. The chances of finding a perfect replacement are nil. There are threads here that show retrofitting a screen door roller, etc.
What I did, once I found the position that allowed the door to be lifted and removed, was to completely remove the old wheels. I then found some fairly hard and slippery plastic and cut it in to a strip that would jam fit into the old slider rabbit. I now use a few drops of silicon/teflon lubricant on the brass slider that the old wheels used to roll on. If it gets hard to slide, I wipe off the slider and put down a couple drops of lubricant.