since you have 2 identical machines try this
if the top draw is failing to empty try this
remove basket and main filter. Now remove impellor assembly. if you dry out the water you will find 2 holes in this well (hoses) one of these holes leads to your waste the other comes forward and comes out where the small mesh filter is. this is the inlet to the pump and sometimes debris can find its way down there. find something softish like a large cable tie and sort of rod it through to make sure its clear
also you can take out the impellor from the lower one and swop them. most times the top draw gets more use as its easier to get at
the lower one sounds more complicated and may be a heat problem as it needs heat to dry
Dave