quite " dangerous " to shift the green arrow without a timegrapher, it has to be moved a very little ( and I'm not talking about millimeters, but less than that ) otherwise you will have a watch that, instead of losing 1 sec per hour ( 24 sec a day ) will gain incredible amounts. Best advice is to get it regulated somewhere, if this isn't enough then get it serviced. or buy a timegrapher and do the regulation yourself