If the safe has a history of being temperamental you could try dialing by slightly shifting the numbers. Example, first dial the combination with the first number one lower. If it doesn't help, then dial the combination with the first number one higher. Do this with each number in the combination one at a time.
I am not familiar with a Chubb or how tight their wheel gates are. I once had a lock on a safe that had one wheel in the wheel pack that would center the gate almost one number off from what it was set at. When that number was dialed perfectly the fence would just barely drop in. I had to set it one number off to get the number I wanted to work each time with normal dialing that may have imperfect alignment. I assume the wheel was made slightly out of spec. It was difficult to get the key change mechanism to disengage and engage on that wheel.