On pressing the on/off switch the machine starts up but switches itself off almost immediately. If the switch is wedged down, the machine will work right through the cycle. If the wedge is removed at any point the machine will stop, but will continue from this same point if the wedge is re-applied.

Is it just a problem with the switch, and can it be replaced independently of the electronics? If so, how do I get at it, please?

The machine is 6 or 7 years old.

John B, September 2009

It's the contacts in the ON/OFF switch, they've worn to the extent that they barely make contact. It's only when you press it all the way in that they stay connected. How do I know ?.......well I've just fixed the same problem on mine. It really needs a new switch, but I took it apart and cleaned the contacts and bent them ever so slightly outwards so the pressure was restored. It looks daunting, but it is quite easy. First disconnect all power (of course !) to the machine, and take off the top lid. There are two small screws beneath white plastic covers on each side of the top. Detach the connectors from the back of the ON/OFF switch, and pull the switch up, whilst levering back the small tab at the top of the switch. Out it pops. Then once on the workbench, prise off the small clear plastic cover over that covers the resistor and red lamp. Once removed, de-solder the resistor and lamp leads from the switch and carefully remove. Next, carefully prise off the back of the switch. You will now be able to see the switch mechanism. Carefully remove the button, spring and be sure not to lose the little disk-thingy that engages with the button to lock it. You can them remove the two moveable contacts. See how the contacts will be pitted and burnt. If they're not burnt out altogether, you can scrape them clean with a screwdriver. To clean the captive contacts, you can scrape them by poking the screwdriver through the tiny holes on the back of the switch housing (maybe that's how the repair man does it and charges a fortune for 10 mins work, and a new switch ??). You'll notice that the moveable contacts are slightly bent. To compensate for the wear, bend them outwards until they're just past straight. Reassemble the contacts, spring and button, and check operation. Check the electrical connectivity with a meter, before you click the back of the switch on again. Re-solder the resistor and the lamp leads to the switch, replace the clear plastic cover and put back in the machine. My advice is to order a new switch and replace as this will innevitably go again, but it'll get you by.

Principes, November 2009