I made the cutout in the panel, following the guidelines in the Installation Manual, except I considered that the cutouts around the knobs in the corners were a bit bigger than necessary. So, I tried to make those cutouts a bit smaller, to have a more visually appealing fit. Then I tried to fit the instrument in the panel. I couldn't figure out how to manoeuvre it into place. It was like a Chinese Puzzle. I had removed the Power/Volume knob at the to right corner, as that shaft fit though a corner. But I expected that the other knobs would just slip into the cutouts. Nothing doing. I removed the Course Select knob at the lower left corner, but I couldn't figure out how to remove the Frequency knobs at the lower right corner
I tried to get it in the hole for 30 minutes - no luck. I finally cracked, and posted a request for help to the RV-List and the Aeroelectric-List. Then I decided to try one more time. Of course I figured it out right away, now that I had asked for help.
How do you get the Narco 122D in its hole?
- Make the cutout at the top right and bottom right the full size called out in the Installation Manual - don't try for too tight a fit.
- Remove the Power/Volume and Course Select knobs (you need a Torx T-5 tool).
- Remove the sleeves over the Power/Volume and Course Select shafts.
- Slip the Power/Volume shaft into its hole.
- Push the unit up against the panel, so the right side of the unit is touching panel.
- Twist the unit so the Frequency knobs slip into their cutout. Enlarge the bottom of this cutout if necessary.
- Slip the Course Select shaft into its cutout.
- Install the two screws, the bushing on the Power/Volume shaft, and the knobs you had removed earlier.
- Note: I didn't have screws that were short enough, hence I had to put washers under the screw heads. I need to purchase #6 screws 1/2" long.
Lesson learned - use the cutout dimensions in the Installation Manual, even if they are "obviously" too big. If you want to make a smaller cutout, try it on some scrap first to see whether it will work.