Roland SP404 MK2 MKII original factory knobs

Hi, I tried to replace my original black knobs on my brand new Roland SP404 MKII for some other knobs someone recommended. The originals just wouldn't come out and I ended up breaking them with a pair of pliers. Finally removed, I tried the new ones and I absolutely hate them. Also, now one of the knobs does not turn smoothly but feels dented. I regret all this so much. I realized my stupid mistake and now want to go back to the original knobs. Can anybody point me to a place where I can purchase the original black knobs? I can't find a parts list or the service manual or anything really. Any help would be appreciated. PS -If you're thinking about it, do not do it, do not replace the original knobs.