[C320-list] Drain aqua lift muffler? Engine won't start after charging batteries overnight

[Dave Hupe]

 Several folks have said they have never used the muffler drain.  As I said, I've checked it a couple times when I think I should drain it after extended cranking, but nothing came out.   So, I am wondering if it is plugged up.  Not having the ability to drain it could ultimately lead to a big problem  (flooding the engine by a backup into the exhaust elbow??). 
I may try soon to unthread the whole drain petcock assembly from the muffler to check out  if it is functional and if there is a backup of sediment in the muffler near the drain. Either situation should be fairly easy to remedy (assuming I don't crack the muffler unthreading the assembly.  Installing a new drain petcock probably would be a good idea too if I go to that level of effort.  Anyone have experience with this?
Comforting to have so many say they also forgot to push the fuel shutoff T-handle back in after shutdown  (and that was why they had hard starting later).
Dave Hupe
1994 C320 (#32)