Also, I see that you have placed a third gatevalve on the output. That is an excellent idea since you can control any effluent at the end of the line. I will eventually place one with a clear tube just to monitor the situation (attached photo). My only issue is the new valve extends farther out and will require shortening the gray/black tube to clear anything.
Also, with the added hose and spray option, cleaning water can be sprayed upstream into the tank drains. Again, Amozon or other.
Again, thanks for the photos, I am hoping I wont have to dig into the valves.