Our Dualit toaster doesn't work. The red light doesn't work. I have changed the fuse in the socket with a working one. The timer turns normally. Yet none of the heating units heats up. Once the bottom part removed, it looks as if all wires are well connected. Any thoughts on the issue? It is a Dualit toaster, three slices, model 31213, Many thanks in advance for your help, Eric

You need to replace the timer-contactor. This part is acting both as timer and electrical contactor. It consist from electrical contact moved with springs on and off. Due to electrical load and extreme heat these contact have been tear out thus they can not contact properly and in your case they don't contact at all.
So from the web page of dualit or ebay you can order A new timer contactor and replace it.

Check the thermal trip, it may need resetting, usualy its coloured white with a small button, its under the bottom panel, good luck.