how do i re start a regulator wall clock?

hi hope someone can help me. i am house sitting for my neighbours while they are on holiday. They have a very old antique regulator wall clock (i believe this is what it is called). the problem is that whenever they move the clock they have to call a man out to re start it for them. however when they decorated last month they managed to take the clock down and put it back without calling a man out. just a while ago i was going to wind it up, but as i opened the door, i thought that the clock was going to fall off the wall,it jolted a bit, and the pendulam stopped. i was wondering if i could re start it myself....if i could please could you tell me how eg is it just a case of moving the pendulum? hope someone can help, many thanks