Was winterizing my new to me 2021 Reflection 303RLS today and encountered a few problems. Thought the red value took the hot water tank and fresh water tank out of the equation but I guess not both were filling with antifreeze when I was winterizing with owners manual in hand and valves set as illustration instructed. Reading online found out another owner had a bad check valve which aloud antifreeze to enter the hot water tank, so the valve does not keep antifreeze from entering the supply line from the hot water heater. Had to replace Grand Design's $.25 plastic check valve with a 1/2" nipple a few weeks ago because it cracked and I did not have access to a check valve at the time. Hot water worked fine after that in fact I have increased hot water flow which was much needed. Well found out that you need that valve when winterizing. So I crimped off the out coming line from the hot water heater while I sucked in the antifreeze. Opened one valve at a time on fixtures got antifreeze to come out every fixture but would not come out of kitchen sink? Water came out of it earlier when I blew the system out with air. Also as I was wintering with valves in the correct position I could not keep antifreeze out of the fresh water tank. Any ideas what to do?