Our dishwasher had decided that it couldn't be bothered, a bit like a teenager forced to do the washing up. Well we were looking around for a way to incentivise it, and CDs of metal rock bands just weren't enticing enough to a dishwasher, so we started looking at illicit substances.
Here's one that appeals to dishwashers. It's very easy to use (you put the bottle upside down in the plate rack and run the machine through a cycle) and it cleans out everything except that annoying bit just under the door hinge which needs a cloth to clean it. What it revealed is that we haven't fitted our filters properly every time, and some bits of plastic packaging (from eg cheese packets) had found their way into the innards of the machine. Before cleaning with this Finish, the bits of plastic would have been covered in grease and stuff and would have stuck in the pipes and small holes, whereas after cleaning, we could see the pieces of plastic and wash them out easily (take the spray arm off, look for the bits, put the spray arm under a tap and slosh to and fro until it washes free).
Will try to keep the filters fitted properly which will avoid the problem next time, but we're certainly going to use the Finish Dishwasher Cleaner more often than once in 2 years. Only down side - you can get two for roughly the same price from Lakeland