Installed a 2nd D10A with remote compass (in March) to serve as the HSI indicator for my GPS. Has worked fine for 9 months. Had an annunciator panel installed to upgrade the panel to IFR connected to the KLN90B (which has been in the panel for 4 years) in December. On a test flight last week, the heading indicator on the D10A sweeps back and forth about 90 degrees fairly constantly. Ideas? :-/