The timer keeps stopping when toasting so have to stand over the toaster or else it burns the toast Can this be repaired?

Because the nichrome wire on one side of the toast has broken.
Its time to get a new toaster.

The best thing you can do is call the manufacturer. It sounds as if it has a default.

https://toasteroven.info/toaster-oven/toast-in-toaster-oven/

https://sensiohome.com/collections/kitchen-appliances

1500 watt six slice toaster oven. 450 degrees for toast, darkness level 4. Both timer and temp knob must be on. Time range varies. low fan level.

You need a new timer should be free from dualit but is not. Its a common problem . I would consider it a design flaw. They at the very least should make it available in the states at a resonable price. You can get a new one on ebay pricey

Probably needs a New timer best price I have found, with instructions http://www.mcssl.com/store/electra-craft/catalog/product/522920765afa4d168f30d465bed95c1a

Dualit Limited
County Oak Way
Crawley
West Sussex
RH11 7ST

Telephone: +44 (0) 1293 652 500

Fax: +44 (0) 1293 652 555

Email: [email protected]

FAQS can be found at http://www.dualit.com/support/2-slice-newgen/faqs#question2 and new timers can be ordered.

The element has burnt out, IF you can get another it is worth repairing, IF NOT, then it is time for a new one.

The timer is also a electrical contact switch. When the timer goes to zero an internal spring force the electrical contact to open so the heating elements to stop heating.
So either the spring stuck so it can not open the contacts anymore or the electrical contacts have been stuck together by elctrical sparking during the on and off.
In any case you must replace the timer switch with a new one since they does not worth to anything else with it.
The operation does not need any profetional skills since it can be remove easyly by removing the bottom panel and be carefull to remove the wires conected to it with clips make some notes so you will put the wires in the same position of the new timer switch.
If you don't fill comfortable with above then let an electrician do it for you.
Good Luck

Your selector switch may be broken if the oven works on selections other than toast.

Dualit service center:
Electra-Craft
41 Woodbine St
Bergenfield NJ 07621
ph 201-439-1700
[email protected]