Cleaning Dried Rinse Aid Out Of A DW
The first thing to always use to clean the inside of a DW is a high quality DW detergent, such as the high priced detergent tablets.
For the sudsing use cooking oil and put down an old bath towel and let the DW run a cycle or two.
Vinegar is ok for mineral buildup, but even for these it is better to use a proper DWer cleaner.