Without direct experience with the No. 1, or knowing if off center primer hits are normal,
It might be that either the channel for the firing pin is slightly off, or the firing pin is slightly misshapen.
How does the firing pin sit in the channel, from the breech side?
Maybe, if it's off center, it can be rotated to compensate.
Or, if the gun shoots ok, leave it be.
Lots of guns have off center hits on primers without issues.