What a thought-provoking question? There often are a myriad of answers that are quickly offered. You know the "usual suspects" like old age, failure to read the instructions, misuse, poor design and the all-encompassing I haven't a clue.
We often then find that what is broke can't be fixed and that is reflected in what is about to happen on January 20th. Even time won't fix that problem. It likely will never be fixed and as we are on the path our founding fathers fought so hard to never happen. But it has happened so strap in for a bumpy and never-ending ride.
So, what failed at N6QW? Well, the power switch on my beloved Collins KWM-2 just failed. Now this is a rather unique "power on" switch and that is why its failure is not easily fixed. Let me explain.
The power "ON" switch is really two switches. In the upper left-hand corner of the radio is a four-position selector switch with 1st position being "OFF" followed by ON, NB and Calibrate. Linked mechanically to that common four position switch is simply a snap action switch much like the power switches that are mechanically ganged to an audio potentiometer.
Two factors are on the path to a fix, with one being this is a common failure on the KWM-2 and the original manufacturer was the Oak Switch company. But the other factor is this switch is unobtanium. I know what you are thinking --find a pot with switch in the junk box and simply pry off the switch and you are there.
Not so easy as most of those switches are only rated for 1 amp at 125 Volts. You need a 5-amp switch to handle peak in rush current and at full output of the 516F2 power supply the draw is over 3 amps through that switch. Another problem is that these switches vary in size so that you need an exact duplicate for the Oak Switch to fit on the mounting plate ganged to the 4-position front panel switch. That is on par to a pair of $1 tickets to see a Taylor Swift concert or that 2029 is just weeks away.
One currently advertised "primo" KWM-2 selling on eBay has this same problem where the seller simply placed a jumper across the switch pins and every time you want to use the rig you just plug in the 516F2 -- not a safe solution nor very elegant.
One intriguing solution found on the Internet is to fabricate a substitute switch using a clever approach. The first task is to find a potentiometer (value unimportant) with an integral 5 Amp snap switch (eBay). The second piece is to acquire a 1/4 inch to 1/4-inch shaft coupler that has 4 set screws (Amazon). You will also need a small piece of aluminum plate to make a bracket.
The plan is to remove the Oak Switch which exposes a short stub of shaft from the selector switch to the Oak Switch. Fix one end of the coupler to this stub. The other end of the coupler is fitted to the pot. Set the 4-position selector switch to OFF and the Pot snap switch to OFF. The Pot is arranged on a homebrew bracket so is aligned to the main switch and a hole is drilled in the bracket plate and anchored to the original anchoring bolt. You will need to bend the plate with a couple of right-angle bends.
This is the approach I will take to fix the KWM2 power on switch. Regrettably there is nothing that can be done to fix the future.