IB-1 Stereo Output Jack help

A customer in the US is scratching his head trying to work out how the output jack (stereo) is inserted in the hole.

I did get one out to have a quick look and it does look appear there's a bit of work to do... perhaps filing out the hole to allow the jack to slide into position.

Here's the part alongside the hole where it sits. The hole comes out in the control cavity.
Attachment 15932

Here is where the customer is stuck:
Attachment 15933
Note: the washer behind the tip is rubber, so it does seem that it will all sit comfortably in there, once you get it in place. It's all just a bit too tight.

And here is the view on DB's finished IB-1:
Attachment 15934

If anyone has done this job, can you please let us know the 'trick'. Then we can save this as an instruction thread for future IB-1 builders... assuming there isn't one already.

Thanks for your help.

I had the same problem. Ended up grinding about 1mm off the edge of the flange to get it to fit. And the rubber washer goes inside the cavity behind the nut.

Sandpaper on a tapered dowel to slightly enlarge the hole??

I have had this with an IB-1 kit. I got over it by using a Dremel with a drum sanding wheel and running it around the input jack hole.
This will only get you 1/3 or 1/2 way in to the hole's depth though. For the deeper part I had to run around the hole with a round file, kinda like draw filing in a circle, this got me enough space to be able to get the jack all the way into the hole. Depending on the type of jack used, you may need to cut the rubber washer that sits behind the flange down to the same diameter as the flange. Either that or you continue to sand/file out until you can clear both.
You need to be really careful either way, it is very easy to distort the sharp edged form of the hole and once it becomes irregular, it would be a bugger to try and get it back to a uniform oval opening.