The furler with the North sticker is a Harken. It's made with an integral turnbuckle. To adjust it, you need to loosen the left hand locking nut and star washer under the drum and the locking collar which is inside the torque tube on top of the drum. The unit is adjusted by holding the stud and rotating the actual drum. It should not really be used to tension the rig, only to adjust it. So your backstay should be loose and you should have a halyard led forward to slacken the furler during this process.
The t-bolt on the bottom of the unit has some marks on the flat side which should not be visible. If you can see them, you have opened the turnbuckle too much.
The stud and that t-bolt should have been started equally and you might want to check that that was done.
The rigger should have measured the pin to pin before he started to disassemble the furler to replace the wire. If he did this, he should have simply reset that measurement before the furler was reinstalled and you should have exactly the same rake as you had before the rerig.