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MB 149 Repair

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The helix rod on my MB 149 has broken. I've purchased a third party part from Custom Pen Parts but now realise that replacing the rod is not a job for a clumsy amateur like me ! Are there any UK based professional repairers on the forum who would be able to make the repair and what would be the cost please ? I say UK based only because it seems post Brexit that it is extraordinarily complicated and costly to send items abroad !


This picture shows the broken part and the replacement part I've purchased.


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  • Ben6


  • ralfstc


  • Dione


  • eckiethump


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6 hours ago, Dione said:

Take a look at this you tube video and you might be able to follow these instructions to do it yourself.


Many thanks. I watched the video but at the relevant point the presenter said if you have this problem, ie mine, then you're in for a lot of pain So best left, I think, to someone who knows what they're doing !

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Have you read this thread? 

Once you understand way the spindle is attached, it seems a lot more do-able. I did this job most recently on a 146, and it's really mostly a challenge because of the need to find something thin and rigid enough to engage with the c-ring and pull it out. Replacement of the parts (using a long thin plastic tube of the right size) is straightforward. The Custom Pen Parts helix is a joy to install and use.


If you want to send it out, Eric in Edinburgh, user name eckiethump on FPN, does three of these in his sleep every night and is much recommended.


Good luck!



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Thanks Ralf, yes the removal of the "C" ring is a challenge, you can for £10, buy replacement "C" rings, I use a suitable sized and cut piece of brass tube then epoxy adhesive installed.If in future it ever needs taken out again, the part soaked in vinegar will release the epoxy. The replacement part you have there is of the Delrin variety, the PEEK ones are worth the extra. These break, due to users continuing to turn the piston knob after the piston seal has "bottomed".

PM sent with contact details.



Ignorance more frequently begets confidence than does knowledge (Charles Darwin)


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  • 2 weeks later...

Good to hear! He's a marvel, that man! (I know he'll read this and be embarrassed, but it's kind of true). Now if he could just support a decent team . . . .


Enjoy your pen, they're a lot of fun!



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