Magnetic Compass Location

I use it all the time.  This is a shot of the airplane a day or two after I bought it. You can clearly see by the photo that there is not a single modern instrument on my panel.  I learned with a chart and an E6B and a compass.  I have a tablet with GPS software but I always find myself looking at the compass to make certain I am flying on the correct heading. My compass is an Airpath Instrument Company (I have forgotten the model #)  They are still out there and they have a website where you can collect information..

My whiskey compass (something cheap I bought from Aircraft Spruce) is located top center of the panel and it is pretty accurate, close enough anyway. I was careful to keep anything iron away from it. The tachometer was relocated to the far left. I do notice that when I pull the starter knob, the compass swings a little, so it doesn't take much to throw them off.

I just put a vertical card compass in a Coupe and it was a royal pain, it appeared that some part under the panel became magnetized, I could take a cheap hiking compass and pass it in front of the and would point to somewhere on the pilots side. It appeared that the tach cable had become magnetized, I was finally able to get it calibrated by moving it to a spot with the least interference. Was even looking into degaussing coils,

My PA-700 vertical compass has never worked well since I have owned the airplane. It is, on average, off by 30 degrees. Its probably over 20 years old at this point so it could easily be a wear issue. The location is at the top of the panel directly in the middle. Has anyone had luck with this compass or even a whiskey compass in the panel? If so what compass are you using and where is it located?