If he really doesn't shed well, you can put warm water in a box (not hot water, the water must be at the gecko usual temps).The level of the water must be at the same level as his belly.Cover the top of the box, and don't forget tiny holes to let him breathe. Let him in the bath for 10 minutes.Then , gently remove the shed with the tip of your finger, or a cotton bud.
The most important parts to check are the nose, the fingers,and the tail, because if the shed dries and stays for too long, it can cause health issues to the gecko.
But don't worry, everything will be ok^^
After the bath, put him on the paper roll, and gently remove the water.During all the process the water must never enter his ears.