How-To: Tighten a Loose Piston Knob

Pelikan M200 Cognac and Amber Demonstrators

Left: Pelikan M200 Cognac Demonstrator, Right: Pelikan M200 Amber Demonstrator


From time to time, I plan to focus on simple ‘How-To’ pieces that address fixes and/or maintenance that can be undertaken by the pen enthusiast at home.  Since I am not a pen repair professional, the advice that I convey should not be construed as coming from such and professional help should be sought for more advanced issues.  I will focus on issues that arise from regular use which can be repaired with a certain degree of ease resulting in a high likelihood of success.  My first such post was about lubricating the piston, perhaps the single most important maintenance a Pelikan piston filler would ever require.  While thinking about this post, I recalled one question that I see asked fairly often and it has to do with a loose piston knob.  While not necessarily affecting the function of the pen, it can be very disconcerting to an enthusiast who wants their pen to function according to factory specifications.   This is a problem that can develop on some models, especially lower tier ones, owing to the fact that they more commonly have a friction fitted or snap fitted piston assembly.  The normal behavior of the piston knob should be for it to sit securely against the barrel and not have any travel or play when the piston is in it’s fully retracted position.  Please note that I am not discussing the normal 1/8th of a turn delay in piston engagement which is actually quite normal.  What can happen though is that travel or play develops in the piston knob, even when the piston assembly is in the retracted position, keeping the knob from seating itself securely against the barrel.

Pelikan piston with friction fitting

Pelikan friction fitted piston assembly


Pens like the M101N’s, M800’s, M1000’s, as well as the Merz & Krell 400NN’s would not be subject to this phenomenon because they have threaded piston assemblies that aren’t likely to back out of the barrel.  Pens that have friction fitted assemblies have ridges in the barrel which the piston assembly locks into.  Examples would include but not be limited to the 400, 120, and 140.  Pens of the M100 through M600 series have the more modern snap fit assembly.  When the piston is actuated, as in the act of filling the pen, the piston can be over-extended which serves to push the piston assembly out of the back of the barrel.  To avoid this problem, you should stop turning the piston knob immediately after the piston has reached the end of its downstroke.  A very stiff piston secondary to a lack of lubrication or a frozen piston due to poor maintenance and dried ink can also cause this issue.

Pelikan M101N Piston Assembly

Threaded Pelikan M101N piston assembly


The ridges that facilitate the securing of the piston assembly inside the barrel can be damaged/sheared, sometimes irreparably.  Also, a pen that has had the piston assembly removed for repair or service a few times can also become damaged.  That is why I stress that it is rarely ever indicated to remove the piston assembly of a Pelikan (If doing so, however, be aware that I have seen differing opinions arguing the proper technique.  Some say that piston assemblies have to be pushed out from the front and others recommend pulling an assembly out from the rear).  There is a technique that can help fix the issue of a loose piston knob but I stress again that I am not a pen repair professional and that any damage that your pen may incur following the advice below, however unlikely, is your sole responsibility.  If you have any concerns or doubts, you should seek out the services of an independent pen repair professional or the repair services of Pelikan themselves.

Pelikan Red M205

Red Pelikan M205. Arrow indicates direction of force to be applied to the piston knob


The Cure:  With the piston knob in the retracted position (piston up), hold the barrel firmly in one hand (a non-slip material that helps provide sufficient grip comes in handy here) and push in on the back-end of the knob, pushing it towards the section.  I recommend removing the nib if feasible in order to prevent any accidents.  Hopefully this seats the assembly back into the barrel and solves the problem.  If this does not re-seat the piston assembly, it may be that there is another problem at work or that the locking ridges may be sheared and thereby not providing sufficient grip of the assembly.  In general, I would avoid any applications of heat by a novice as it can easily warp a barrel and render a pen damaged beyond repair.

One response

  1. Pingback: A Tale of Two M600’s « The Pelikan's Perch

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