The glass bath case can well limit the water to the combined bath and shower. You may need to adjust the door if there is a sliding door in this bathtub case. When people go in and out of the shower, they use the door to stabilize themselves. This may cause the wheels on the sliding shower door to not align. Adjusting the shower door is a simple thing so it can run smoothly again. Check the top and bottom tracks for signs of debris. Use a vacuum cleaner to remove any dry particles. Mix a few drops of detergent in some water. Clean the track with a sponge or rag to remove any dirt and soap dirt. Use cotton-Clean the gaps that the sponge can't reach with a cotton swab or a small bottle brush. Rinse clean with clear water. Find the top roller of the sliding shower door. All rollers should be in the track.
If one or more of them are not on the track, please lift the door to the frame high enough to get the roller back on the track. Like you, lower the door to a lower track again. If necessary, unscrew the screws that hold the bottom track in place to remove the door. When you lift the door from the tub shell, carefully tilt it. Lower the door to the old towels or sheets you put on the floor. Check the upper roller. Try applying a small amount of spray lubricant on it. If the wheel is no longer easy to turn, please proceed with the replacement. Mark the position of the screw that keeps the defective upper roller in the proper position. Unscrew the defective upper roller. Fix the new rollers in their position and fix their connecting screws in the approximate position of the old screws. Hang the door again. Reconnect the screws that hold the bottom track in place. Slide the door back and forth to check its operation. If necessary, loosen the screw that holds the roller in place slightly and adjusts the angle of the door slightly to the left or right. Tighten the screw again. It may take several attempts to get the door completely right.