On the longest strings, the angle between the front of the instrument, the bridge and the hitchpin is too straight, which doesn't give enough tension on the bridge.
Therefore, there's the backpinning : adding a pin to the bridge in the low pitch part of the harpsichord, in order to add the missing tension.

I made mistakes on this part : I didn't follow exactly the good angles to drill the back pin. As a result, there is too much tension on some wire.
Nothing broke, luckily, but I don't know how it will react after some time. ^^'

Still, it was the last operation for the stringing.