It is possible that machine was restricting the amount of water artificially, to comply with better standards. I did an experiment with mine - you need to time when washing cycle ends and before rinsing starts, and then top up the water inside through the detergent compartment, all 1-2 liters in total. It indeed improves rinsing, but is very annoying to do in practice (hard to time correctly), so I stopped after a few tries.