red light wont stay on?

My GHD 3.1B straightners have packed up, red light wont stay on unless i hold the extention part that goes into the plug.
Have bought a new plug but still not working even when i fiddle with the extention.
Have had them for about 4 years is it best to get a new pair or could they be repaired.
Can you help, trying to save myself the cost of a new pair.

Kind regards