I have a Parker 51 gold stub nib whose previous owner took a knife to the slit and opened it too far. Now the capillary action isn't consistent. I have the nib off the pen and can get the tips somewhat together but the slit is still too wide at the middle of the nib. Gentle pressure on the sides mid-length along the tubular nib isn't doing anything. I thought I'd better stop and get some professional advice.