Nothing like some real life scenarios when checking out a new lessor for my Twin Cessna. After departing KSBA, we wound up with reduced range, late night flight, followed by a winter front. Our plane was to land behind the weather, fuel, climb to FL210 to top the weather and land at Boston. Enroute we had a gyro failure and we were faced with a socked in Northeast. Nothing like landing at Boston Logan in minimums partial panel to keep you on your toes. I have never been so happy to be on the ground in my flying career. Turned out the slaving mechanism for the HSI had failed and thanks to a phone consult with Robin Howard of Howard Avionics we were able to reset and continue the flight back to the west coast.