E-NR SN23M321GB FD 9411. Just three years old and finding food remnants and tea mugs not completely clean. Both spray arms rotate freely and function, filters cleaned thoroughly, impeller checked for blockage and rotates freely, heater appears to work OK, and at end of cycle water drained away. Water inlet and outlet appear fine with no blockages or kinks. Crockery and mugs feel a little ‘grainy’ to the touch. Tried various all-in-one tablets with the same result. Crockery, knives and forks, mugs and glasses washed – no pots or pans. Any help or comments really welcome. Many thanks.