Hearing aid repair

[Don42]

My hearing aids have little pull tabs to help remove them from my ears. Ya don’t want to pull on the wire that goes to the behind-the-ear electronics. The pull tabs are just bits of monofilament with beads on the end.

One of mine broke off right where it enters the ear mold. Decided I’d better fix it. The VA would fix or replace it but it’d take a month.

The tricky part was drilling out the broken stub. The monofilament is 0.022” diameter. It had broken off flush with the surface of the ear mold. I used a #72 drill bit (0.025”) in a pin vise, turning it very carefully by hand. Monofilament is softer than the resin from which the earmold is made, so once I got it started it was self-guiding. The tricky part was getting it started.


I only had about 3/8” of the drill protruding from the pin vise, to minimize likelihood of bending or breaking the drill – which would have been quite unfortunate. I went in about 3/16” and decided to quit while I was ahead.

That done, I nipped off a little piece of 0.022” monofilament (30 lb test Trilene fishing line) that I have on hand for exactly this purpose. Took that to the grit blast box and roughed up a little bit of one end with an “air eraser”, a device that looks like an air brush but it shoots very fine abrasive powder. I wanted to give the mono a bit of “tooth” for glue to grab.


That done, working with a magnifying visor under bright light, I managed to get the piece of mono inserted into the hole. That took a bit of fiddling as you might imagine. Imagine threading a needle where the eye in the needle is only a couple of thousanths of an inch bigger than the thread.

Then I put a very small drop of UV-curing cyanoacrylate (super glue) on the wound and cured it with UV light. Then I made a tiny knob on the other end with a soldering iron (just touch the mono to the soldering iron tip for half a second) and then put a big drop of the UV cure stuff and cured that.

Voila!