Ben, I have a similar edge sander (different brand), it also had a small twist in the platen and in the table. I did exactly what Jim suggested to the platen and to remove the twist from the table I shimmed one edge up with a few strips of thin paper and then retightened the bolts. You want to check the sander table against another known to be flat surface like a table saw top or jointer table before you attempt to straighten the platen. I didn't have to deal with a dip in the table though. Both errors combined resulted in a 1/8" - 3/16" gap on the idler side of the machine and now it's dead on perfect.
These machines come all out of the same 'hatchery' in South East Asia where QC is not necessarily part of the vocabulary, in other words we get what we pay for.
Edit: I should have used winding sticks to check for twist, could have saved me a lot of time trying .