By watching the chalk mark while winding, you can count the number of turns applied, and confirm the number later. My standard-size door (7 foot height) with 4-inch drums has a nominal wind of 7-1/4 or 7-1/2 turns, which leaves 1/4 or 1/2 turn at the top-of-travel to keep the lift cables under tension. After 7 turns on the first spring, I clamped down the set-screws, weighed the door again, and found a lift of about 100 pounds in reduced weight. As expected, this wasn't quite half of the full 238 pounds, nor would it leave any torsion at the top-of-travel, so I added an 8th turn. The door now weighed 122 pounds on one spring, which was ideal. After winding the other spring, the door lifted easily, with only a few pounds apparent weight. This confirmed that the spring choice was properly matched to the door design. I engaged the electric opener trolley, and adjusted the opener forces down to a safer level suitable for the new, improved balance. The door was now ready for return to service.
These springs weighed in at just over 9 pounds each, including the winding cones. They are covered with a light film of oil, and at this point the job starts to get messy. The manufacturer has painted them with a "225B24" part number, which no doubt indicates the 0.2253 inch wire size, 24 inches long. Perhaps the "B" indicates the 2-inch inside diameter. Both the left- and right-hand springs have this same number on them.
The "safety issue" trick: Another tip-off is the use of language like "safety issue". This is meant to trump any objections you might have to a costly repair bill. Don't be manipulated by the suggestion that you are risking disaster if you don't buy something expensive. Even if you think the risk is genuine, get another estimate, and tell the second repairman you are skeptical; every technician loves to prove the competition made a mistake.
First and foremost, a garage door, by design, contains springs designed to balance your door and make it easier to lift. Those springs are under incredible amounts of tension. If a spring breaks or is improperly released, it can cause incredible and potentially fatal injuries. Keep in mind, when working on a garage door spring, it is likely that your face and head will be close to it, meaning that your most sensitive area will be in the direct path of the released spring.