Dishwasher repair

[blk]

Dishwasher won’t drain at end of cycle. I’ve checked/snaked drain hose from unit to sink and no clogs. Check valve from basin to drain line isn’t clogged either as water does partially drain partially filling line, however, I believe this is from head press in dishwasher basin only. (Additionally, when I detach drain line from water housing and manual actuate line, it eventually drains entire basin). My only conclusion is the drain pump is not working, although, the impeller is not blocked and I can manually rotate. "Assuming" my trouble shooting is correct, how would I test drain pump to be sure? If not correct, other options? Thanks, BLK.