Having trouble with remote operated black tank valve

I had the same issue with the black tank on my rig a couple of months ago. I dropped the belly, pulled the valve, cleaned it, lubed with silicone spray, and replaced the seals. It is now very easy to operate. Both my forward grey and black tanks are 3" valves by Valterra. My rear grey (kitchen) is 1 1/2". I have no personal experience with electronic valves but I figure there is just more to go wrong with them so I'm sticking with manually operated valves.