Probably some of the heater elements have broken. Over the years, four of the five elements on my 4sliceBread machine broke (the little heater wires are very fragiile -- trying to remove a stubborn bit of burnt crust can be enought to snap one, especially if you're poking the crust hard with something like a metal knife). If an element breaks, the bread slots to either side of it only toast one-sided (assuming that the *other* elements are not broken). There is one "centre" element between each breadslice slot, and an "end" element at each end. New elements can easily be bought on the internet for not much money -- but you need to know how many "centers" and how many "ends" you want. I am not a mechanic, but I took my Dualit 4slice apart, with no instructions, and found it pretty straightforward but a bit fiddly to gain access to all of the elements apart from the end element nearest the timer dial and light, which I couldn't work out how to get to (behind the casing there is a riveted chassis, and the chassis seemed to get in the way of the nuts at that end). Having taken it apart, putting it back together again was easy enough too afterwards. The nut/bolt/washers used to connect the heater elements to the metal bridge-bars that keep them in the circuit is a little fiddly -- you don't want to drop any of the bits onto the carpet, so do it over newspaper or a bench where you can see them easily if you drop them. I found it helped to switch the toaster on and check the new elements are working before I put all the casing panels back on, and getting the main curved sheet of metal back in place is one of those jobs where you first get all the screws in a little way, and then tighten them down later. But above all and always: remember THIS TOASTER IS MADE OF METAL AND USES MAINS VOLTAGE so for everyone's sake,especially yours, KEEP IT EARTHED. If you don't know what that means, don't even try to fix it yourself. I'd say if you have any doubts about your own ability to do this job, buy the heater elements on the web and then take the broken toaster plus the new elements to a competent electrical-repair tradesperson.
DaveC
September 2006