how can i fix my biasi 24s?

hi ive got a biasi 24s, which sparks when i turn it on but doesnt fire up. after a few seconds it then cuts out and the red light comes on, on the front panel. someone told me it might be the thermocouple, ive since bought a universal thermo, but cant see it being the right part, do i need a special one. can anyone help please?