replace roller on sliding wardrobe door that is within door frame

[nicolebyerlee]

Please help! I’m trying to replace the broken roller on a wardrobe sliding door. The door is mirrored and the roller and cartridge seems to be slotted within the frame with grooves. I’ve tried unscrewing the screws but the cartridge is still not able to be removed due to being within the grooves. Please see photos. I don’t want to pry the frame open as I’m scared I’ll break the mirror. Most videos on roller replacement show the cartridge exposed on the back of the door, not house within the frame. Any help would be greatly appreciated. Thanks in advance