Replacement part for Thorn M30/42 Boiler?

I recently had my Thorn m30/42 boiler serviced and was informed that a part was very worn/corroded. The part in question is the bit where the flames come out, there are several outlets in a row and some have corroded badly and now it burns noisely. Corgi registered fitter serviced and checked it and advised replacing this part. Does anyone have any idea what the part is actually called and where can I get one. I wish I had a diagram or something.