Rangemaster 110 lpg about 10-11years old?

My clock timer has stuck on auto timer, so the ovens will not work or ignite, cannot seem to get the top off to access timer to replace, I have a hot plate and a griddle on the right hand side and 4 gas burners on the left hand side, can anyone tell me how to get the top off, again the call out is too expensive or are there any instruction I could access on the net.