Long story short, I had to unlatch my dishwasher the other night just after it started to drain (just installed new disposal and did not tighten the drain hose where it connects to disposal

) When I started the dishwasher back up it would not, and still will not, drain. Everything else is ok. I have been looking at message boards for possible problem. The solenoid seems to be working fine and motors and pumps are running. How can I tell if it us just the piston and nut assembly for the check valve other than just replacing it?
Thanks
Model
HDA3400G02BB