How can I fix my Chorus II flame igniter??

I'm not sure if Chorus II is the make or model of the oven. Its is quite old and in a rented house where I can't find a manual. The igniter button will not start up the flame anymore and I now have to use a lighter or matches which isn't very safe when lighting the oven and is very inconvenient. I have been told I need to replace a battery but cannot find anywhere that the battery could be!
I would really appreciate some help from somebody that might be familiar with this type of oven. Its driving me crazy!!!