I have a 1990 Gulfstream 232 with twin Yamaha 150 HPDIs. My boat sat in the water for a while when I had some health issues and now I have a problem. The tilt motors on both engines are straining to raise and lower the engines. I have two batteries and two Perko switches so I've tried each battery on each engine and both batteries on each engine. I even tried a new larger battery. My suspicion is a bad ground somewhere but where would that occur so it would affect both engines? In the binnacle maybe? Any adcie will be appreciated.