Maytag Stacked Washer won't complete rinse cycle...

Hi,
I have a Maytag MLG2000AWW stacked washer/dryer. The rinse cycle won't drain completely on any setting even max extract. There is a hum sound but I can't determine if the drum is turning. I took the front panel off and there doesn't seem to be any obstruction in the drain tubing. I don't know how to see if it is an electrical issue or if I need to replace the drain pump. The drain pump isn't all that accessible as it is attached to the ground in the back of the machine. Any ideas? I also can't run the washer with the front panel removed and I don't know how to run a diagnostic cycle...the paperwork is pretty useless.
Thanks for any input you might have...

 

Sounds like a partially clogged pump. I just cleaned one that was filled with pieces of thread and lint.
There is also a check valve to keep wastewater from returning to machine.

 

Sometimes there is a panel in back to access pump. Not on all washers, Take the hose from pump to tub off pump side and put your finger in pump to see if clogged also check hose. Careful there could be up to 20 gallons of water in washer. I use a wet dry vacuum to get most of water out.