A shower door that keeps falling off its tracks and has to be lifted, shunted and tugged every time you get into the shower is not only irritating, it can also be dangerous. At best it could damage the tracks to such an extent that the whole door falls away from the shower unit. At worst it could mean the door falls the other way - possibly on you. Either way, it's far from an ideal scenario.
Here's a quick guide to help you fix the damage and prevent an accident. All you need is a screwdriver a level and a little bit of time.
Check the levels
Place a level on the vertical inside section of the profiles (not against the wall as the profiles are adjusted to level variation in the wall levels). Also place the level on the top of the profile running parallel to the ceiling. If either of these are out of level your doors performance will be compromised so in that instance remove and adjust the wall profiles to get the framework level.
Check the rollers
Make sure the roller mechanism is sitting as it should at the top of the door. If it is not sitting on the track correctly it can be guided back into place with a firm grip and a bit of muscle. Lift the door to get it back onto the track. Test the door action a few times to make sure it is sitting on the track properly. If this doesn't work, try to adjust the rollers instead. While you are doing this you might like to add some silicone grease to the tracks to lubricate the rollers movement.
Remove the door
If there is still a problem, the next step is to take off the door(s) so you can adjust the rollers. Use a screwdriver to remove either the guide rail running on the edge of the door or the one that sits in the centre of the base track. With these guides gone you should be able to carefully lift the doors off the track and lean them against a wall.
Test the rollers
With the doors removed you now have easy access to the rollers. You can test them to make sure they are rotating smoothly and operating as they should. If necessary you can spray them with silicone lubricant to help them turn.
Adjust the door
Finally, you can try raising or lowering the doors and testing whether this adjustment makes a difference. Use a screwdriver to loosen the screw holding the roller and adjust it within the slot. Keep making small adjustments and replacing the door in the track each time until it runs smoothly and securely. Don't forget to replace the track or guide before you finish.