Servicing a pen usually involves; complete disassembly; ultrasonic cleaning, replacement of worn/petrified internal components; polishing; reassembly; testing; nib-alignment and tuning.
 

Disassembly

Taking  an eighty year old fountain pen apart is not always as easy as it sounds. Many were glued together and others will be stuck together due to a build up of dried ink.

The secret is patience. If the pen is made from plastic or metal then the first stage is to soak it in water (often for several days). This is not practical with rubber pens (it causes oxidisation) or casein and celluloid pens (it can lead to cracking).

Next some heat is judiciously applied to melt any shellac or similar glue. Again this is dependant on the material: celluloid can burst into flames; some plastics melt at fairly low temperatures.

The section is separated from the barrel by hand, then the feed and nib are carefully hammered out.

The remains of old ink sacs need to be removed from the barrel and if the pressure bar is corroded or damaged it also needs to be taken out.

The cap clip may need removing if it requires straightening or tightening. The method varies depending on the make of pen. In the worst cases the inner cap needs to be removed first. I try and avoid this unless it is absolutely necessary.

Some makes of pen require special tools for disassembly. If these are no longer available they may need to be hand made.
 

Cleaning 

Cleaning is either carried out by hand or using an ultrasonic cleaner. 

Replacing internal components

Ink sacs solidify after a number of years. Thankfully replacements are available in a number of materials and sizes. The replacement is glued in place using traditional shellac.

Piston washers usually need replacing as do traditional cork seals. Again we are lucky that there are some dedicated individuals still making these for many vintage pens.

The parts of a pen may have slightly expanded or shrunk over the years. Occasionally this can lead to leaks and it may be necessary to fit a rubber o-ring. This may not be authentic but it is not visible when the pen is re-assembled.

Polishing

Most pen bodies can be polished using several grades of micro-mesh and then a specialised polish applied with a soft cloth. The amount of polishing will depend on the state of the pen. Care needs to be taken to protect engraved logos etc.

Nib alignment and tuning

As vintage nibs were usually made from gold they are malleable. Often the tines of the nib have been slightly bent so that they are not aligned correctly. This results in a scratchy writing experience. They can be carefully burnished back into shape using a magnifier to check the alignment.

On well used pens the tipping material may have worn unevenly (for example if the writer held the pen at an unusual angle). It is possible using micromesh to smooth the tipping material to a more even shape.

Extreme cases

Pens with cracks or major scratches/dents in the barrel  are not usually considered good enough for resale, but if it is a treasured possession it may be possible to repair cracks and fill scratches and dents  so that they are only visible under maginification.