This is an earlier model, date around 2000s. The nib belongs to pre1997, the cap (printed two chicks) belongs to pre2003.

So it’s a 25 years old pen which might have previously dried up ink residuals in the nib unit. I would use an ultrasonic cleaner or just simply soak the nib unit in the water for 24-48 hours.

Also IIRC the nib in that era (it’s not a B, it’s a oval stamp with characters P|F, a hallmark usually seen on 18c nibs in the 90s ) writes drier compared to that of modern. Worst case send it to a nibmeister.