A tech has to deal with the need for the new seat to take a set when tuning a freshly serviced reg and has a couple options as to how to do it.
If the second stage is adjusted for minimum cracking effort (not always a good idea) it will freeflow after the new seat takes a normal set.
You can deal with this by setting the orifice in a bit farther (about .03-.04") to anticipate where it will need to be once the seat does develop a seating groove.
Alternatively (and ideally) you can wait for this process to happen by letting the reg set for a week with no air pressure or let it set for about 8-12 hours with pressure on it.
Some people will set up an adjustable reg to achieve the minimum cracking effort out of the water. It then breaths very nice on the bench under normal atmospheric pressure, but may freeflow in the water as the water pressure on the diaphrqagm will be greater than the pressure on the exhaust valve (in a face down position) and if the difference is greater than the cracking effort, the reg will freeflow. What the diver then has to do is detune the reg with the adjustment knob to achieve a cracking effort of anywhere from 1.0 to 1.4 for a balanced second stage.
Most balanced second stages have inhalation specs that essentially call for the cracking effort to be set in that range in the first place rather than to a lower cracking effort as the lower effort just is not useable in the water and this may be the situation with your reg and it may well breathe just as well as before when actually in the water.
But if you are not sure what the inhalation effort is, or feel it breathes harder in the water, take it back to the shop for adjustment. They may have just set the orifice in a bit too far or failed to make a final adjustment after the seating groove developed in the seat.
Ideally a shop will give you a sheet with the before and after specs of the reg. If you like the way your reg breathes when you take it in, you can also aske the shop to set it up the same way again after they service it. If your shop can't do this, they do not know what they are doing, or are ill equipped in terms of diagnostic and testing equipment, and you need to find a new shop.
Personally, I will set my personal regs up so that they freeflow very very slightly when the adjustment knob is all the way out. But then I need to turn it in 2-3 turns to stabilize the reg under water and avoid a freeflow. However as the seat wears a bit over my 100-130 dive season, I often need to move the orifice in a bit farther to maintain an adequate adjustment range. For a customer, that is not always an option and the factory specs are usually a better way to go.
