Segal Deadbolt thumb turn knob is loose

I have a Segal single cylinder deadbolt lock on my front door and the thumb turn knob on the interior of the door is very loose. I can still get the lock to engage and the key operates the bolt just fine, but I am worried that the knob might disengage and I won't be able to open the lock.

I took the deadbolt off the door and looked inside the deadbolt. Everything is covered by metal and I am afraid to open it up in case I can't get it back together. Any ideas on if the thumb turn knob can be tightened or should I just get a new lock? I can't find any good diagrams online of how the thumb turn is connected to the casing.