Do you think that was the problem all along? Or did you just change the orientation of the external when you moved it? Regardless, I don’t like putting them out there on that tail boom. There’s vibration there even on a smooth-running heli when the tail blades “bite” in a turn or whatever.
Not related, but I found a good use for old APM’s with an internal compass yesterday. I put one in a Trex 500L Dominator, no GPS/external compass, no MavLink - just using it for a FBL unit. Just two flight modes - Stabilize and Acro. It works perfect and handled hard 3D no problem at all. Cheapeast $30 FBL unit there is.
Now I’m trying to figure out how to get it to work with a Spektrum DX-6i with a Orange 615 receiver with CCPM output. Just thought I’d throw that out. If you got an old APM2.5 or 2.7/2.8 and a heli you want to use for fun flying. It was easier to get that APM tuned to match any of the modern FBL units than it is to tune a Pixhawk with the newer versions of Copter. Took all of about 30 minutes to tune it in and it “just works”. Those are some tough old boards, not near as finicky as a Pixhawk 