SN10 Remote Repair

My SN10 remote has lost the knobs and shafts from two of the rotary
switches. One of them kept falling off from about day one and I've
stuck it back dozens of times, but it has eventually disappeared into
the dirt on our field. A second one is now showing the same symptoms.

This looks like it could be a not uncommon problem and I wonder if
there is an easy fix that doesn't require it to be sent back to the
manufacturer (I'm not keen on converting worthless US dollars to Euros
right now).

The switches look like standard components that should be readily
available and easily replaced by anyone competent with a soldering
iron, perhaps with a more robust equivalent.

Anyone know of replacement components available in the USA?

Mike