I've had a Krups 874 for over 15 years. Most of the problems are caused by limescale building up inside. The steam nozzle is blocked easily, it needs unscrewing (remove rubber handle first) and cleaning out with a pin/needle. Unscrew the plate where the espresso chamber attaches and clean that. Then run through a kettle de-scaler a few times on both espresso mode and cappuccino mode to flush out the debris. If the pump isn't working, then you'll have to undo the bottom panel (a few hollow point Torx anti-tamper screws here - easy to get bits for, e.g. CPC) and you'll see a thin clear pipe, this needs flicking with your finger to knock the debris from the pump, you may need to do this a few times. Oh, don't forget to remove the water container from the back each time you flip it over. Obviously, there is 240V AC inside, so ensure it is off when accessing the guts. When the steam attachment is run in hot water mode, make sure you have a something able to cope with the steam/water rush. The simple cure for these problems is to descale and clean after 20 or so cups, just let the water run through and discard. Most people just buy a new machine every few years!
David
December 2016