My valves were leaking a little so I opened it up to accessed the valves and took them apart, cleaned and put water proof grease on them and put them back together. Also took the time and shortened up the cables to the proper length for each valve , lubed them with dry lube and reinstalled.
They all work very smooth, better than when it was new from the factory.
luckly just the gray valves needed attention the black was ok after the cable was lubed.
No leaks now.
I also installed a valve at the dump end of the pipe right behind the cap, if you have a small leak it will contain it no mess when removing the cap.