Hello, I upgraded my panel and autopilot several months ago and over the past couple of months have been going on training flights to learn how to navigate and how to do fully coupled IFR approaches. The autopilot worked well initially but then a few weeks ago it began to malfunction on one of my flights. I set the autopilot up to follow GPS LNAV and "ALT" for vertical mode with target altitude of 2000 feet. Then after climbing out to ~1000 feet I engaged the autopilot and it wanted to dive pretty aggressively. I disengaged and recovered and continued on my training flight without using the autopilot. 20 minutes later after setting a GPS course for KPWT, I again engaged the autopilot and it behaved in a similar manner. I manually held altitude and attempted to trim up to see if that would offset the autopilot. This did prevent it from diving but the altitude wandered up and down and I could feel servo slippage. It did seem to follow LNAV but not vertical. Oddly enough, the "Level" button did seem to behave properly.

I stopped using the autopilot that day but tried it again on subsequent flights and it continued to have the same problem. Then I decided to reload firmware on the SV-Net devices using the "update" feature under admin settings. I re-calibrated after this and then went for a flight. The autopilot worked fine again for a few flights, then started misbehaving again. I went back into the Admin settings to see if I could run a diagnostic test but that doesn't seem to be an option. I *did* notice that when the SV-NET devices are listed that one of my servos shows channel "B" in red. all other devices have both A and B channels shown in green, so this seems like a problem. Can someone tell me what this means? And perhaps how to run a diagnostic on the servo?

Thanks in advance.

Jeff